As I posted earlier I think the best bet in that category would be the Hantek 6022be USB scope. There's a a lengthy thread here about it and you can find them on eBay for less than $60 USD.
At this price range it's even more important to check the specs and internal details with a fine tooth comb. For instance the VDS1022 has such luxuries as AC coupling that the Hantek doesn't have (
) and a rather more realistic 100Msps for it's quoted 25MHz bandwidth rather than 48Msps for the quoted 20MHz on the Hantek. There's much more going on in the Hardware (FPGA controlled with on-board buffering rather than a basic Cypress EZ-USB micro), Hantek quotes 1MB buffer but that's just some arbitrary S/W buffer size they picked on the PC, not device memory, in reality it doesn't have any. This makes it far more reliant on USB performance and s/w polling (detailed in the Hantek thread). Check out the VDS1022 teardown thread and discussion that I linked in reply #5.
Sorry to say it, but if you've set yourself a $100 max limit, then you need to squeeze every cent of that limit to get the best capability (= useful life to you) that you can. Either that or just blow your limit out of the water and get a Rigol as ez24 said the other guy did. Either way, please come back put us out of our misery. Edit: Of course I'm talking 'new' here, the second-hand working or fixable 'lucky strike' is still the other viable option.