I've always liked the tokina 100mm macro for it's affordability and build quality. You could also look into extension tubes or reverse mount adapters if you just want to be able to focus closer to the subject.
You could also look into a used nikkor 180 or 200 macro off ebay, the older ones without AF don't run too terribly much.
Depends on what you consider breaking the bank, but I've seen tons of great work done with the Tamron 90mm. Looks like you can pick one up on eBay for ~400 which IMO isn't too bad for a specialized macro lens.