One CM vendor, eGrail, has quietly begun offering a 90-day guarantee: if you are not completely satisfied with the product, you can return it for a full refund, no questions asked. Of course, by that time you will have probably sunk so much time and effort into integration and training that you would be loathe to take eGrail up on the offer. Nonetheless, it speaks to buyers' skittishness about CM purchases and demand in the marketplace for an easy "exit" from a relationship if things don't work out....
Visit the eGrail website.