Hot water coil or side arm?

I just re- plumbed my old tarm boiler after moving it inside to my basement. It used to be out in the detatched garage. I need to do some thing for domestic hot water. I used to use part of an old steel boiler with a coil in it as a side arm but it's just too shabby now. Once again I would like to do this on the low budget side. Can someone direct me to the home made "tube in tube" thread. I may try to build one. If I remember correctly there are several different ways to fabricate one. Are there any other ways to do it other than the traditional flat plate hx?
Mike

Heres mine.Can't get much more "low budget" than this but does require some tools.

http://www.hearth.com/econtent/index.php/forums/viewthread/26838/

I just bought pipe at HD and sweated it all together, my inside pipe is 3/4, and the outer is 1 1/4, the inner pipe on mine is the DHW pipe. my shell heater is a preheater for a tankless hot water heater.
I found I couldn't get the whole joint hot a once, I had to work around the joints with the torch and solder. I also bent the cold water (middle) pipe slightly so when the cold water made the inner pipe shrink it wouldn't put tension on the ends. I read somewhere on here about someone making their own and that the ends kept failing from thermal differences.
here is a thread with pics.http://www.hearth.com/econtent/index.php/forums/viewthread/8168/P0/

also http://ecorenovator.org/forum/solar-hot-water/636-diy-solar-hot-water-heat-exchanger.html
shows someone making one.