The goal was to create a fully functioning "Minimalist" SSB transceiver using something different than the currently popular bilateral (Bitx) topology and in doing so use the minimum number of transistor devices. The linked webpages (separate page for each module) describe a fully functional and operational 20M SSB transceiver that uses a total of 7 transistors, Five of those transistors are 2N2222A, the 6th is a 2N2219A and the 7th is now a RD006HHF1. With some shopping all seven can be purchased for under $10 total. The output power is 4 Watts with the RD006HHF1. If you stick with the IRF510 the cost is under $5.