I am an advocate for using a wheelchair to conserve energy.
I think doing so has been instrumental in allowing me to do the things I have been able to do. I do not know for sure that using a wheelchair to conserve energy has played a part in my relatively slow progression, but I think that it has.
For most folks, maximizing insurance benefits when getting a wheelchair is very important. As others have written, be sure to understand the insurance implications of having them get you a wheelchair early.
Insurance companies (and Medicare) are interested in getting you only what your current need requires. If, for example, they approve a scooter today (because that is all they think you need today), that could interfere with their willingness to pay for a power wheelchair in the future. Make sure you understand what they are willing to do before you commit to getting a wheelchair through them.
I have also found that buying used wheelchairs costs me just about as much out of pocket as getting one through insurance. For example, I paid about $3,000 out of pocket for my power wheelchair procured through insurance.
I have privately bought 3 other used wheelchairs, for $500, $850, and $3800, respectively. I have had to spend a bit on each wheelchair to get them fitted for me and outfitted with the equipment that I desire (about $1,000 per used wheelchair).
My used wheelchairs all had low miles on them when I got them (unknown miles, 35 miles, and 26 miles, respectively). The one with unknown miles probably had far less than 100 miles on it, based on the motor brush wear. That means all three used wheelchairs still have a LOT of life left in them.
Getting a wheelchair early has benefits beyond conserving energy. It allows you to get used to using a wheelchair before doing home modifications and getting a wheelchair van. It also allows you to adjust the wheelchair exactly to your needs while you still have the ability to easily get in and out of the wheelchair. Many adjustments require repeatedly getting in and out of the wheelchair!
Good luck deciding what to do. Please post any specific questions to this thread. I will be glad to help out as I can.
Steve