I'm wanting to do macro photography with my K1000 and the 100/2.8 SMC-A Macro lens seems like the ticket here. Pricing information seems hard to find, or I'm just not looking in the right places. What would you folks say is a reasonable price for one of these? On another note, do you think I'd be better off with my 50/2.0 and the Auto Bellows? Thanks for the help!