I think I have found the cheapest source of the modules (a little over US$10 each) but shipping is a bit high for single unit quantities.
Another reliable source is SDS Hobby but they're a bit more expensive.
Right now I have about 20 pairs of transmitter/receiver modules (as a result of trying different suppliers to verify their ability to ship and their prices) so I'll probably offer those to readers at whatever I paid for them -- although it'll be a limited offer because I'm just getting rid of the excess I've accumulated.
I'm hoping that once I've published everything, someone will start putting kits together and selling them for a (very) low cost so as to help those who don't want to be scrounging around looking for bits all over the place.
Someone ought to be able to make a small profit and still provide a very cheap kit (compared to individuals sourcing the bits themselves) because most of the parts are far cheaper in quantity.
For example, the regulators cost just 12 cents each in quantities of 50 but if you want to buy just one or two you'll end up paying $2.50 each.
If anyone's interested in doing this then they're welcome to drop me a line to talk about what's involved. I'm not taking a cut or commission on anything and not charging for use of the designs.
RCModelReviews.com, just the facts.