Recommendation

[ulrichsd]

Macro Extension Tubes & Close-up Lenses

This will explain things much better than I ever could (at the bottom)

Since you are adding a filter it is going to reduce IQ, and I've never used these cheap close up filters, but I'd imagine you get what you pay for. However, for the OP's stated budget and the fact that your retain the ability to focus and set aperture (compared to cheap extension tubes) it'd be a good place to start. If he chooses to upgrade he'd only be out $10 on the close up filters. And he'll have a nice camera for all other types of photography.

Here's a good comparison of macro lens vs close up filters. Basically, a low diopter won't add much magnifcation, but reduces the focus distance without too much loss in IQ. The stronger diopter setting and the more magnification, the more the IQ suffers.