Well for starters I don't spend much more than $15 to $20.00 on a used vacuum from say the thrift shop, garage sale or where ever. Secondly I'am very fluent in taking stuff apart and doing the reapirs and checking over the whole machine.
I have an older Panasonic McV5218 Upright or something like that. It is on its last legs now, but it has proved itself a very fine machine for over 12 years.
I prefer Bagged machines, never will buy a Bagless, the dust bin can build up with bacteria after a while and emptying it is a nuisance and the hepa filters need frequent changing.
Having said that Ricaar and Simplicity are very good Vacuums. I would not buy a miele they tend to have some quirks that can and will eventually haunt you returning to the vacuum shop for costly repairs.
Buy an Uprite with a Floor/Carpet selector on the power nozzle, that way you can also drag it outside to clean the car without the power brush churning away.
Its also a bonus to buy a machine with a metal brush roll as these have removable brush strips which are cheaper to replace than the whole brush roll. And do maintenance on the Brush roll portion of the machine every 6 to 12 months depending on how much you use it. And keep the motor pre-filter clean, this will increase the longevity of the motor. Its always better to change bags when 80% full so as not to cause over heating.
A quality machine if looked after will last over 20-30 years. Thats my 2 cents.