The old Mission 700's weren't a bad speaker - I've still got a pair in a third system running an Arcam amp and CD player.
Whether or not the amp can run the speakers is more down to the impedance/efficiency of the speakers. My main amp is a Sugden with 25 watts but it still goes loud enough without any hassle.
I had a pair of the Monitor Audio BR2 for a while and they were good wee speakers. They cost me £75 second hand and I think thats the way you're going to have to go to get a decent set under £100.
Edit: If you want a bit of cash spare then
these would be good - might go as little as 20-30 quid and you can put the rest of the cash to someat else in the system.