the Mono is about $190 at City Music. you get what you pay for, the thing has so much padding it's ridiculous. the only problem with it is that with all the padding, you can expect it to be quite bulky. i have trouble fitting my bass into cars sometimes.
for $50-$80, your best bet would be the Warwick Rockbags. be sure to get the ones with more padding, there are a few variations in the Rockbag line. i have no idea where to get one first hand though. they come up on the buy/sell section occasionally.