What lens do you suggest for a Nikon d3100?

I have a Nikon d3100 and I use the 18-55mm lens it came with. I want a lens that focuses more on details, like dew drops and veins in flowers, ( a macro lens?) and a lens that has a strong enough zoom to be able to take clear shots of the moon, and other distant objects. I was looking at the Tamron 70-300mm Di LD Macro Lens w/ Motor 3 Piece Kit for Nikon D60 D40 D3100 on ebay ($189 - is that a good price) but I've read some poor reviews on Tamron lens. What lens do you suggest that fit my specifications?

I would suggest a "Macro Lens" I have the Canon Rebel t3 & I use that lens for really small objects & it works really well! Also the "Zoom Lens EF-S 18-55mm 1:3.5-5.6 IS" Lens! Hope this helps!