I have a bunch of Crown brushes from the Italian Badger and Studio Line. I think you have to order $25 minimum and the shipping is around $7 and you have to deal with their weird website, and calling them during business hours to verify your order and give your credit card number over the phone, but most of the brushes are under $5 and are decent quality. There are some other threads on Crown. I love the synthetic brushes and many of the eye brushes are pretty good as well. My favorites:
IB103 Flat Bronzer - for applying powder foundation
IB106 Angle Blush
IB119/C200 Deluxe Crease - for applying crease colors lightly for daytime/for blending (the C139 is comparable and a little stiffer)
IB116/C138 Round Tapered Crease - more of a pencil brush
IB111 Round Angle Blender - can't see from the photos, but it's a doe foot shape and is my favorite blending brush of the moment
The whole C170-series, but particularly the C170-4, which is the perfect size for concealing blemishes
C217 Bent Liner - omg makes gel liner so much easier
C250-0 for really precise lines
R105/R106 retractable lip brushes - if you have lip palettes, these are the bomb. You can put a bunch of lipstick on your brush, retract it, and put it in your purse for an evening out...then you're not stuck carrying the whole palette. They're pretty elegant, too.
The spoolies, lash combs, etc. are super cheap.
The C313, allegedly their MAC 187 dupe, is super cheap and works to apply light, diffuse layers of powders, but it's not as thick or as sturdy (or as beautiful) as the 187. I've heard it's the same one sold by Coastal Scents. I think you could get the same effect or close to it, but I have never actually tried because I always reach for my 187 instead.
I have not been impressed with their kabukis or other brush lines, but you can get quite a few brushes for ~$30! I have duplicates of all of my favorite brushes, which saves me time on brush washing because I wash them all at once at the end of the week.