Technology and especially software change very fast. As a software consultant you are expected to be on the cutting edge of everything. Ongoing learning and skill improvement is a critical area which you need to include both the budget and time for in your projections.
* Go to (and when possible speak at) industry events
* Read new books (and review them on your blog)
* If you are a visual learner (like me) take subscription to Video tutorial sites
For example I have a subscription to Peepcode, Thinkvitamin and Lynda.com. I learn well with videos and these sites allow unlimited access to their videos to improve my skills.
For our team we have a book budget and everyone can request books (or e-books) they want. Have a generous learning budget. Money spent on skill up-gradation (for you and your team) is the best money consultants can spend.