While the situation with your previous artist is very unfortunate and unfair to you (or so I can only assume), you should not take that out on future artists by lowering your budget. It's not fair to the future artists that someone else screwed up. I would suggest replenishing your budget prior to looking for new artists.
Also, if you have a budget in mind, it's really important that you post it here rather than look for bids. I, personally, am more likely to lower my rates to work on a project when I know what the budget is upon submission.
That does suck to hear about the previous illustrator. May I ask what happened? Were there creative differences or did they just up and leave? While I do feel that many artists are reliable and talented, there are certainly bad apples out there who ruin it for everyone else.