I have a few ideas which may help.
First of all decide what he needs. Some models have a weight limit of only 200 pounds, most are around 300, and some go as high as 450.
Generally a three wheeler is more maneuverable than a four and easier to control. However, if balance problems are involved a four might be better.
If you are going to be transporting it in a car trunk, or otherwise breaking it down for transport you would want a lighter machine that is designed to be easily broken down. Note that the person doing it has to have reasonable strength, as some parts are
heavy.
Other than breaking one down, there are several ways to transport one. With an SUV or van you can use a ramp or a hoist lift that swings and places the
ECV inside the vehicle. There are also lifts that will work on almost any truck and larger cars (requires a Class 2 hitch or higher) that will carry the ECV on the outside.
You might want to look at pridemobility.com (
ECVs), Bruno.com (ECVs and lifts), or Harnar.com (lifts) for more information. Note that they do
not give any pricing information on their web sites. But you can find dealers, including some that carry all brands.
Comparison shop for pricing. Often you will be able to get a discount if you buy both an eCV and lift at the same time. Negotiate.
Additionally, especially if you have or a getting a new car most manufacturers will give an allowance of about $1,000 to assist in making the car accessible (such as installing an ECV lift). This is completely unrelated to anything a car dealer offers.