Wow $75, I could go crazy with that!
hydrangea is correct about the kits, I bought the one for "dyeing in baggies." It's a great method, very easy to use and will save you money in the long run. I believe it comes with lemon yellow, turquoise and fuschia. You simply always need to have those colors. The book that comes with it is fabulous, lots of great info on mixing colors...
I dye a lot and find that I do not need their special laundry soap, instead I use 7th Generation. Additionally, I purchase sea salt in bulk from my co-op (it does not contain Iodine.)
Other colors you might want to consider are a nice deep green (new emerald green is nice,) a deeper blue (like ceruleum or saphire), a bright red like Scarlet, a deeper yellow like Marigold (it's gorgeous when mixed with a bit of Fuschia.) 2 oz bottles are more than sufficient. Most of these colors are $3.95, but the blues are $6.95 -- and worth it if you want a deep (dark) blue.
One thing I bought that turned out to be really fun, were Squeeze Bottles
You have to mix the dye in something else and then use a funnel to pour it into the bottle.
Do experiment with the colors, some just don't do well. IE mixing Scarlett with lemon yellow is not pretty, but with Fuschia it's this gorgeous salmon color.
A technique I made up is to get one of those clear plastic storage boxes for sweaters and place a piece of clothing in it that is already soaked with the "chemical water" and put some extra "chemical water" in the plastic box. Then using the squirt bottles full of dye, squirt the fabric! You can draw, you can make dots etc. Then you can either roll it up and put it in a zip lock bag or you can squish it around to blend the colors. You have to use a lot of dye if you want an intense color though.
As for batik, you can buy at Dharma or at a craft's store some bees wax. You can melt it in a coffee tin that's sitting in boiling water or use an electric fry pan on low. To get the wax on the clothing, you can buy a tool for it at Dharma called a Tjanting
or you can use a plastic spoon or something and just pour it on (not very precise, but it works!) The only bad thing about batik is getting the wax out. The secret is not to use too much wax (so that it totally saturates the fabric) but rather just enough for it to sit on the fabric. Then by washing the dyed fabric a couple of times in really hot water 95% of it comes out.
Oh, this is the kit I bought and love: Procion Baggie Method Starter Set
It's well worth the $28 with the book.
So what to dye? And how to maximize your money?
Get some friends involved. All the "clothing blanks" deeply decrease in price once you order a dozen of any cotton items. I only dye kids clothes and have found the tshirts, dresses, cardigans and pull on toddler pants to be wonderful.
Oh, and I used the baggy method and the same dye to do a couple of the silk cut velvet scarves. The only difference was that when I prewashed and post-dye washed them I did it by hand.
Good luck! And I hope this wasn't too much information!