the TD 3 modile, last time I checked with EZI music (you can click on he banner on SOFT home page). they quoted 600. but still if you are starting from a satch i suyggest you go for the complete TD3 KIT. around the same price if you're going to start from zero. a td3 kit=1.8k
an rythm traveller e-drum conversion: td3 module: 600, RT: 700, misc. electronics and cable, 100. hi hat pedal, 70 total: 1.5 k..and pls do remember you must have time, proper tools, some electronic basics to complete the project. and of course some mistake will happen eventually. but if you have an acoustic drum, you just got to buy the mesh skin head. and again go find out yourself at the friendly music shop about the price and availability
Go and check yourself out how much you need to suncsribe to the site, i forget how much.