The patches my kids got had a sticky back on them, so all you did was stick them on the ears. I'm sure they'll let you buy just the patches. I heard somebody saying some of them were iron on patches and you had to do those yourself, they wouldn't put them on for you.
We got our ears done in April of this year. My daughter got A hot pink beanie with pink faux fur trim, lime green ears (and she's not even a DISser!), her name stitched on the front (in black thread) and a Goofy patch on the back. Hubby got a navy beanie, Fireworks ears and his name stitched on the back. (I got the same as he did). With 6 ears, 3 beanies, 1 patch and 3 names, we spent just under $50. Oh, and I think ALL three beanies we chose had chin-straps (us adults wore the straps under our hair instead of our chins).
I debated getting a classic black beanie with my name on it, but I think the price was $9.95 for one. I decided to splurge the extra buck or so for a fancy set of ears.
Regarding the patches, we had our patch ironed on while we waited. The patches are sticky so you can stick it where you want it to finish designing your hat. BUT--you may want to re-iron them when you get home. DD's fell off a few months after she got home (though, she likes to break things, so she could have picked the silly thing off!)
The neatest thing, though, was having cast members comment on our ears. Back in April is was brand-new, so I don't think a lot of CMs even knew about this! When we stopped to ask a CM about the fireworks, he commented on DDs ears. DD took them off and handed them to the CM, who put them on and modeled for me!