My hard to buy for sister has a birthday coming up very soon. She likes hair and skin care products and has been diligently working out with a trainer lately. Any ideas for birthday gifts in the $75-100 range? Preferably something thatqualified for amazon prime but others considered. I am desperate!
gift card for athena or prana?
I like that idea. I would love a gift card for lululemon. I don’t shop there often, but if I had a gift card I would.
I would love to be 49 again…
Maybe a gift card for Nordstrom’s; nice store but a bit expensive for my tastes. If I had a gift card, I’d have to find something there. 
Since your sister likes hair and skin care products, she might like a subscription to Birchbox. Samples can be customized. There are 3 subscription levels ($30, $60 and $110). With promo code BBMAG, they currently will also add a free subscription to either Glamour, Vogue, or People Style Watch. One of my sons got his girlfriend this gift for a birthday and she loved it. https://www.birchbox.com/
How about making a gift basket for her? Here is what I will be doing for my good friend who is into exercise and skin care: I will get her the book by Matilde Thomas and some of her wondeful, fresh-smelling, nonnastychemical skin care products.
Here is the book, full of advice that makes lots of sense (ignore grape detox though):
http://www.amazon.com/The-French-Beauty-Solution-Time-Tested/dp/1592409512
This smells like pomegranate and makes the hands buttery soft.
And this sampler set:
OTOH, a Lulu gift card is always well recieved! 
Baby Foot!
One of those magic microwave egg cookers, LOL. 