Anything can be done if you spend enuogh time, sweat and money, but think of it this way - those things are made of components that the big co's order in huge bulk, probably at great discounts, from their long time suppliers. Can you compete with the prices - or will you have to buy everything at top retail price one at a time?

we just did the closet maid system at lowes. we did the expressions (i think that is the name) and it has everything you could think of! the closet is about 10 feet wide and 4 feet deep so we did both of the sides and the back. it cost us about $1000, but i feel it was worth every penny! if we had just done shelves ourselves, it would have saved us about $500, but nothing would be very organized.
another option is ikea. they have some amazing closet organizational systems. but you have to go into the store. you can't tell anything on their site!
good luck!

If you want to get an idea of how much one will cost, many of the online closet sites will let you design your own closet online and calculate the cost. www.easyclosets.com is one that I know of. For comparison purposes, I think that they're cheaper than California Closets but more expensive than the kind you buy at HD or Lowes.

I used Oranizedliving.com to purchase a system called FreedomRail. Much better quality than closetmaid and less costly than Easy Closets. It was on sale at the time for 20% off.

I also used an IKEA Bureau in my walk in. They have one that is 14 1/2 inches deep. I just changed the handles to match the set of FreedomRail drawers that I installed. It saved me $$ to use the bureau.