An idea for a great gift for your wife might be a mini-vacation! Select a nearby get-away and book an extended weekend. If that doesn't work, perhaps a certificate to a day spa, or a new laptop would be suitable. Find something she really enjoys, and run with it.
A super special super cheap gift is pictures. You could make picture frames and put pics of you two together. You could make a picture book. I don't know but a picture's worth a thousand words and memories! This might not be her main gift, but she'll love it!
Ok, u said budget... No big deal I'm the same way lol my husband asks me what I want and idk I'm not very picky I guess anything that I know he spent time thinking about. For my bday he made post it notes they all said I love u and he put them all over the house. U could do something similar on the mirror say she is beautiful. A woman needs to know she is wanted and not always needed. Xmas can b hectic too a day just relaxing at home or a nice walk together through the woods or at the park. A lazy day watching movies snuggled next to u. Things u think about ;-). Good luck!
I noticed you said you were on a budget, so I wouldn't personally want a massage if it were me. It would be a great treat but it would be over as quickly as it started. If you are on a budget, your wife probably doesn't shop much for herself (we tend to put oursleves at the bottom of the priority list when it comes to spending money), so I would recommend either a gift card to her favorite store or planning a day out with a nice lunch for the two of you and a shopping trip. That way the two of you can spend time together, and your gift (shopping) will be something that will last for months to come.
A masage sounds nice and if u do it urself its Free!!! Grab some her lotion and rub her down after her shower and dont forget a foot masage! Or u could make supper and buy flowers to set on the table! Turn off tv and turn on some music u both like! Or make her a coupon book maybe write a day ull do dishes or make the supper or a rainey-day movie with her