Tying can be expensive, but you don't have to break the bank.
For the two different applications, dry flies and bass poppers, you might want to put the $'s towards feathers with good dry fly quality. For dries you'd want stiff barbs of uniform length, flexible stems, and feathers with barbs that correspond to the hook sizes of the dries you'll be tying-- generally 1 1/2x the width of the hook gap. Typical sizes of dries for trout might range 10-20 with mostly sizes 14 and 16's and as you get into tying on smaller hooks adding 18 and 20's. For bass poppers you can get away with less expensive feathers because you'll be relying on the foam or cork popper bodies for flotation, so feathers with softer barbs will be fine, and longer barbs would match up well with the larger hooks you'll be using for bass.
For dry flies you might want to consider getting something like the Whiting Introductory pack consisting of four 1/2 capes for $60. These are a pretty good deal and comparable to two whole Whiting Pro Grade Capes that would normally go for around $40 each. These are available in many fly shops, but here's an example from Bears Den, a fly shop in MA.
Whiting Introductory Neck Hackle Pack ! at BEARSDEN.COM
Whiting also sells 1/2 saddles in an introductory pack, but the advantage of capes is that they will tie a wider range of fly sizes than saddles, typically dries size 10-18 or 10- 20, and will also have a good amount of feathers you can use for buggers or streamer wings. Whiting saddles will typically tie dries strongest in 2 sizes-- (often 14 and 16).
If you go with an Introductory pack, I would specify these colors when you order: grizzly, medium dun, brown and light ginger--- these will cover you for a wide range of hatches and popular patterns using these colors alone or in combination (Adams = mixed brown and grizzly).
As you tie and pick through these 1/2 capes you can replace them down the road with full capes or saddles depending on the sizes you end up tying, and your budget.
For your bass poppers, a decent and inexpensive option, is to buy strung saddle feathers- These are dyed over white feathers and come in a variety of colors. A 1/4 oz of these strung feathers generally goes for around $4, and will give you plenty of feathers to play with for bass flies, and bass size poppers. These feathers generally have long, soft webby barbs for size 2-6 size flies (when wrapped around the shank). These feathers also come in handy if you tie streamer patterns like Lefty's Deceivers and other meaty stuff for freshwater bass and a they have a ton of uses if you tie stuff to chase saltwater fish. Here's an example, again from Bear's Den, but most fly shops will carry this stuff:
Strung Rooster Saddle Hackle - 5 to 7" ! at BEARSDEN.COM
If you have a local fly shop they should also be able to give you advice on what would work well for the patterns and sizes you plan on tying. And if you don't have a local shop, consider buying from an online fly shop as opposed to a big box store, with a 1- 800 number that you can call and ask questions before you buy and talk to someone that actually ties flies.