Fast but heavy glass

Hey yall,

So I don't know what to do. I would like to buy all the lenses and cameras in the world so my arsenal would be 100% watertight and fool proof but as money and more money is fleating I will have to settle with one lens at a time. Currently I am lacking a good wideangle to mid standard lens, making my scenic and landscape pics kinda crappy as far as quallity is concerned so I have been looking at Sigma's 10-20mm 4-5.6 which seems to do well for itselve, But this lens is not very fast. There will be a new 10-20mm coming out this summer from sigma that has newly coated glass and a faster constant Fstop of 3.5 which excites me but I know it will be closer to a grand and I feel that is too much for my wallet right now. I think my option will be to get the 15mm f2.8 because of price, but I dunno if it will be wide enough or long enough to fill my real needs making me need another lens at around 30mm to fill yet another area I lack in focal length... Oh well, I should stop thinking outloud and go make some money to buy toys:-P