Few options:
If you have a decent DSLR, a macro lens and copy stand is an option some are exploring to good success.
Option 2 - Buy a scanner. Epson V700/V750 currently about the only game in town under £2k. I use a V750, using fluid mounting, a passable 12x16 is possible (shot on Tri X or Neopan in a Leica). Frankly, it's not quite as good as I'd hoped at 35mm though for 6x6 it's great. A Nikon 9000 is MUCH better and much more expensive.
Option 3 - scancafe.com
If you buy, I use Silverfast Ai, set to "HDR" mode, invert in photoshop then resave as tiff and edit in LR prior to output. With positives, this step won't be necessary.