Well, I have a little experience in this department because I just built my own press this weekend. For a great set of plans follow this link -
http://www.theoxfordgroup.com/bow-press.pdf

The plans tell you how to do everything and how you can customize it to get an x-press fit if you like. I customized mine for my Tribute and it works like a charm. Have pressed 4 different bows and it performed flawlessly. An x-press will set you back about $500. Total cost for materials was $70 for my press. I would do it again in a heartbeat. However, if you do not have all the tools and equipment to do the work and/or you do not enjoy this type of project you will be better off buying one. It took me almost 12 hours from start to finish and that did not include the time involved in getting the materials. If you fall into this catergory then I recommend buying a hydrapress from this website -
http://www.hydra-press.com/index.html

Cost is $170 delivered. I don't know how he sells it for this price. I wouldn't build and sell them for that. The plans above are for the hydrapress. Buy it or build it - a great press!