Pretty much all I do is techno of some sort (from an arrangement standpoint) but when it comes to creating my sounds I like using sounds that aren't from the genre, such as those in glitch, dub step, bass (I.e. Dynamix 2) , ambient, dub, industrial, and some alternative (i.e., my bloody valentine, a...

I've been pretty happy with Driven Machine Drums and Driven Machine Drums Strikes Back. Your best bet is to download the Demo samples and check them out.

http://www.drivenmachinedrums.com/

Another bundle of synths to consider is fxpansion's dcam synth squad. The last time it was on sale it was $99.

d16 Group's Phosycon is good too. To emulate the 303 I think you really need to focus on the sequencer because most people won't notice the difference between a 3 pole and a 4 pole filter.

It's a non-exclusive license, so you can release the track on another label too. Save whatever money you receive from this for the time you need a lawyer/solicitor to review a real contract.