Buying Electric Cars
Let's start with the easiest. In this era the major car companies are moving to adopt electrification. This word covers all forms of adding electric drive units into cars, including "regular hybrid cars", plug-in hybrid cars, battery-electric cars, and even fuel cell cars. The different auto makers are moving at different speeds in this project, but they're all working on it. The range of models currently available is limited so you may be unable to find the type of car you prefer with an electric drive train.
The easiest areas to buy an electric car are those where government requirements are the strongest. Here in California we see all kinds of electric cars on the road because the government requirement is the strongest.
What you must look for are the dealerships selling electric cars. Do they list electric cars in advertisements? If so that's a sign the dealership is putting in more than a token effort to sell electric cars.
What you want is enough dealer knowledge to help answer any question you might have, especially regarding charging station installation at home. And, when it's time to service the car, does their service department have expertise with electric cars?
The only practical difference between buying an electric car and gasoline car is charging station installation. The most convenient place to charge is at home, and therefore one must consider the charging station options.
The cheapest home charging arrangement is the "line cord charger" that comes with the car. It runs at a very low charge rate, but can be powered by a power outlet that is probably already near where your car is parked.
If you want faster charging see: Getting and installing at home electric car charging equipment
There are special considerations if you live in an apartment complex, townhouse complex, condominium complex, or the like. In such cases you do not have as much control over your parking spot and may not have a power outlet that is under your control. See: Apartment/Condo dwellers - what to do if you cannot charge at home
Other than the charging station installation, the purchase process for buying an electric car is exactly like buying any other car. You're choosing between a lease or purchase, whether to get a car loan or not, and so on.
The final thing is understanding how refueling an electric car differs from gasoline cars. In both cases we are refuel our car, with the only difference being the type of fuel. There are considerations around range and recharging time to understand. See Learning Range Confidence
Buying Electric Motorcycles
You might think an electric motorcycle is impossible, and you would be wrong. There is a small industry of electric motorcycle makers and every year the bikes are becoming ever more credible.
The major motorcycle makers are not selling electric bikes, at this time. There are rumors that Yamaha, Harley-Davidson, Honda, etc are working in that direction but very little is in the public.
Instead, one must turn to the handful of small electric motorcycle manufacturers. In all cases these companies solely manufacture electric bikes, and are dedicated to the cause.
Zero Motorcycles https://zeromotorcycles.com -- Based in Silicon Valley, this company has the longest history with electric motorcycle manufacture. Their current range includes street bikes (Zero S and Zero SR), dual-sport bikes (Zero DS and Zero DSR) as well as bikes closer to dirt bikes. The SR and DSR are higher power bikes that can do pretty well on the race track. Zero has dealers all across the USA and in many other countries.
Energica https://energica.eu -- Based in Italy, this company has a respectable history of electric motorcycle manufacture. They got started with bikes for track racing in 2010, and by 2015 had developed a bike for sale to the public. Being an Italian company the styling is very nice. They have dealerships in many countries.
Lightning Motorcycle https://lightningmotorcycle.com -- Based in Silicon Valley, this company has put in over a decade of development of what is arguably one of the fastest motorcycles one can buy. For example on land speed racing at the Bonneville Salt Flats, they set a 215 miles/hr land speed record, and at the Pikes Peak International Hill Climb in 2013 they beat the entire motorcycle field by over 20 seconds.
Buying Electric Bicycles
Electric bicycles were first made in 1895, before you claim that an electric bicycle is even less possible than an electric motorcycle.
In some areas, like China, electric bicycles are extremely popular. Tens of millions are sold every year, with hundreds of available models to choose from. In other areas folks know very little about electric bicycles.
In the New York City area electric bicycles are widely used by delivery riders for restaurants. During 2017 there was controversy raised over these riders with claims they were riding irresponsibly. However the city worked out an agreement defusing the controversy.
Generally an electric bicycle in the USA is limited to 20 miles per hour top speed. In the USA electric bicycles are allowed to have a throttle, and it's possible to ride one without pedaling.
In Europe the rules are different, and with a lower power limit than is allowed in the USA, and a requirement that bicycles not have a throttle. Instead European electric bicycles must use the "Pedelec" design, meaning that the bicycle senses when it is being pedaled and adds power to match the pedaling.
There is a growing list of bicycle dealerships selling electric bicycles, and a growing list of models available in the USA.
Be leery of the electric bicycles imported from China. As I said, they're extremely popular in China, but the Chinese electric bicycles tend to be lower quality.