EA3GCY sells a range of QRP kits including single band, single PCB, SSB transceivers for 20m or 40m. These look easy to build and test and good value for money. Currently there is a 5% off offer running too.
See http://ea3gcy.blogspot.it/2013/03/iler-20-4-5w-qrp-ssb-monoband.html .
See http://ea3gcy.blogspot.it/2013/01/iler-40-4-5w-qrp-ssb-monoband.html .
He also does a CW kit and other accessories. Look out for the ILER range.