there was a lax ~$25USD iirc budget last year.
some went above it, some went below it. but it was more of a "lets hope everybody gets something and we dont have any deadbeats that just want stuff"
I think the give within your means statement is always appropriate. If you can only afford $25, including shipping, only spend $25. If you can afford more and want to give more, do it. I know that since I have a job now, I may spend a little more on my person than I did last time or may have to send less hand made stuff.
If you don't have a ton of money, there are some cool things you can make that aren't expensive. A wood wrist wrest, for example, can cost under $10 to make depending on what supplies you have on hand at the time. If you can draw, I know plenty of people would love to have a piece of artwork. If you have nail polish and crap caps lying around, you can try your hand at making some fun polish caps. Just think of the things you can do, of your skill sets, and you can find something great to give, regardless of your budget.
basically, this. stalk your elf so u can get them something they want that's around the budget you want to spend.
don't send them an mx keycap because you had an extra and all they use is topre or alps.
And don't be that guy who sends the ****ty caps from you SP crap bag and nothing else. There were some of those last year and I know some people felt taken advantage of because of stuff like that.