The one piece of advice I would give you with a limited cash supply (& I've been there)...Shop, shop, shop...Get the best that you can afford and also be innovative.
You can make your own jerk strings, I found years ago a thing called a Weasel Ball (shaker) at swap meets...I just cut the back out of decoys, placed them inside...Sealed up others that went into the water directly...Paint your own decoys...Lots of stuff that really costs very little....A good thing to learn to do is air brush...You can make any old decoy look great
Back to your original question...Commercially made jerk strings are around $35.00 (Tanglefree)...You can also get baby Mojo's for like 2 for under a 100 bucks...You can make them remote controlled by buying the remotes on line...I think they're under $10.00...Wire them up yourself...Pulsators are good, but pricey...You can make them yourself, but it's a project...And I don't like the big battery packs.
I don't think high dollar decoys are necessary either...Places like Academy sports & Wal-Mart sell their teal for $30.00 a dozen (less on sale)...Widgeon, pintail, mallards a little more.
Heck, if you live in San Diego, I'll give you a bunch of stuff, including spinners...