My two cents worth on this conversion/discussion (and that IS what`s its worth!): The proverbial "You get what you pay for."
There is a reason professionals detailers use top-grade (IE, high dollar) equipment: Time is money. Buy the best you can OR maybe you can find a good used polisher/buffer on E-Bay or Craig`s List that some professional no longer uses. Again, it`s used and you get what you pay for.
I am always taken aback when noobies have this expectation of producing professional results with "inferior" products and equipment, but perhaps more correctly, it is the lack of experience and use of said products and equipment that produce less-than-expected results. Trying to buff out a self-healing paint on an older Infinity with a Walmart-purchased $38.00 buffer and supplied pad and OTC Turtle Wax compound can be a headache and disaster. While I cannot dis the Original Poster (OP) for their request of how to maximize his capital investment in a polishing machine and what that choice should be, experience will play as much as a role in using it as the polisher itself. This forum contains ALOT of help in that area; IE, what works for what situations, but ultimately the end user will need to develop that experience on their own. Much like watching a video or reading about driving a golf ball; until you do it yourself, you are not a true "golfer" and it will take a lot of practice at a driving range or on a golf course before you become proficient at it.
So, here are some things to consider with a polisher/buffer:
1) Machine ergonomics; IE, how the machine "fits" you`. Is it heavy in weight? How is it balanced? Does it vibrate a lot? Where is the speed control and ON/OFF switch located relative to my hand or thumb when holding the machine?
2) Build quality (the "you-get-what-you-pay-for" to some extent; knock-offs or copy-cat polishers CAN be well built, but the attention to detail or materials is why it is priced as it is)
3) Warranty and service (which is why Griot`s Garage machines are highly regarded)
4) Available backing plates and sizes (If your vehicle has a lot of deeper "shapes/curves" or air scoops in the bodywork, a large diameter backing pate will not access those areas, if that large diameter backing plate is all that "fits" a particular machine)
5) Pad considerations (Thick pads, thin pads, Closed-cell, Open-cell, Microfiber, yes, even wool or synthetic wool, not to mention the diameter(s) [size(s] to fit the backing plate(s) you choose.
Add to that the type of paint your vehicle(s) has (have) (Hard Clear Coat, Soft Clear coat, Self healing Clear, Single Stage, or lacquer (if it is an older classic car) , and even the vehicle itself (a compact car versus a (very) large two-ton crew cab, extended bed truck) now you have even more variables to consider in selecting a polisher and associated hardware/equipment. The one-size-fits-all approach, while it may seem appropriate, may not product the desired results and lead to more frustration than many expect.