I'm thinking of the sort of scope that gets routinely thrown out, working, by schools, colleges
Speaking as an employee of such an institution, that stuff generally gets surplused (sold at auction in lots). Those things are expensive when purchased, and expensive things get tracked (long past the point when they still have value, in many cases). You may have to look for a notice of a sale, buy a box/pallet sized lot, find one that works, then probably get probes somewhere else (since students seem to destroy them at an alarming rate). Sell the remainder one at a time on ebay, maybe even making a buck along the way.
Businesses, on the other hand, may toss the stuff, or give it to an employee.
I already have a scope, but I'm watching for that US$150 USB logic probe to come out with mac/linux versions of the software. I've had enough SPI and I2
C problems that it may be worth it.
Hackaday has been featuring a few projects with a project known as the "bus pirate" (PIC-based, IIRC). I haven't looked at it myself, but it could be worth a look if you're in the market for a digital signal analyzer on a budget.