Another part should be modification: on ebay you can buy really cheap pedals. For example this week I bought a Ken-Multi/monarch Distortion for Eur 8,50 plus shipment. This boxes are not so bad. For example the PSK SDS-2, SDS-3 or SDS-5 (seems to be now the roque SDS-5 can be easily be modified to be a Rat. They put in this unit since yearsa 470 Ohm instead of the 47 Ohm resistor in the gain section. If you change it, it should sound like a rat... If you can buy a zvex unit you also can use a plastic-boxed. If you don´t like it, there are also a lot of metal-boxed units on ebay.
I've pointed to this before but it is true that instead of fighting the diy and boutique scene who allegedly would be stealing all their business, the big pedal manufacturers concentrate on making cheaper and cheaper pedals that are just ok. For the price a diy could not even buy the hardware to make a box.
Another subforum, I know, but we do like to at least try and keep the information accesiible in some way, which is not always easy with a forum.
Please feel free to make suggestions and comments about the idea in this thread. And have fun... but remember cheapo cheapo pedal only.