Well, as long as you've got a welder, a good drill (drill press recommended), and a grinder you can do it yourself. Word of warning though, they still end up costing a lot! I made cardboard mockups of mine and then ordered all the metal pieces pre-cut from onlinemetals.com because I don't have a plasma cutter or a metal brake that will bend such beavy steel. If you have access to a hydraulic metal brake and a plasma cutter you will definately have an easier time and it will be less expensive and time consuming. I had a TON of pieces to weld because everything had to be cut and welded to make bends instead of just bending.
Anyway, my prototype set is done except they need to be painted. I'm going to be making another set for a club member which will incorporate changes to make them simpler, stronger, and easier to install (I hope). So, take into consideration that your prototype set won't be perfect either, although I still intend to use mine on my truck since the changes aren't anyuthing critical to performance.
The two key design features of mine are that they have no bolts exposed to impacts at all and two bolts on the front plate release it so it will pivot down to do oil changes. Also, since I don't do much rock crawling, I made the main plate a bit narrower than the Skid Row plate for better ventilation and recuced heat buildup under the truck. I believe the plates to still be similar in strength to the SR skids though and they cover the critical components that I am mostly worried about.
All in all, I think they turned out pretty good for my first set, but they would probably be an embarrassment to sell. I figure I spent about $200 for steel, bolts, welding consumables, etc.
And I know XOC will make some smartass comment
about my welding so I'll get this out of the way in advance...