Isa
If you go the DSLR route, I would pick up a D50 instead of a D40, great price ($550 with Nikon 18-55) now that it just got discontinued. You should also get a Macro lens for it if you want to take good Macros. I have one on ebay right now.
Link to auction
Or just get the S4 (or new S10) which will fill the bulk of your needs for under $300. A simple light box like this with an inexpensive tripod does wonders
LINK