Carol, you have hit on one of the most difficult decisions cookbook authors need to address. Jason and I have struggled with this decision for each book that we have published and so far have made the choice to go with B&W. Although with the improvements of color printing technology the costs are becoming closer every year.
In fact, we are currently exploring the idea of providing one of our cookbooks in both color and B&W to see if our readers are willing to pay the premium for color.
If you do decide to go B&W, then I might suggest you consider doing two things we do to assist our readers in getting access to color pictures from the book. The first is to provide a "Photo Gallery" on your website which contains all the color pictures from your book. This is the gallery for our
Sous Vide book. This gallery is also a very good marketing tool for your book as well.
If you have a Kindle version of your cookbook you can take advantage of the Kindle MatchBook program that allows purchasers of your paper back to buy a Kindle version at a reduced price. This allows them to view the pictures in full color.
Good luck with your decision and your cookbook.