if you want small players...
You need to think very differently about the contracts and the way systems are specced.
Certainly in some of the ones I was involved with, there was no way little guys could bid (except as a subbie). Building a new benefits system is going to be a larger chunk of revenue than you'd be comfortable with for a small supplier. Unless you radically changed how you build big mission critical systems.
For those with lots of bad things to say about the big boys working on big systems - you have a point as lots of those went wrong (not all though - ESA worked very well for example) but let's not forget smaller firms screw up as well (iSoft for the NHS, COINS, etc) with the same bad results.