The 3* Makaha Resort on the west side of Honolulu, Hawaii has some decent sub 100$ nightly rates(89$ for aaa/senior).
They have pretty good reviews with a 3 1/2 * rating on tripadvisor
There are a couple of good buy X amount get x amount gift certificate deals. Both these gift certificates get mailed in about 1 week and have additional charges of $3.75 and $5
this one is buy 25$ get 50$ gift certificate in which you can buy 4 total (you can use two vouchers per visit)
this one is buy 50$ get 100$ gift certificate in which you can buy just 1(you can use 1 voucher per visit)
So if you go for 1 day you can use either coupon. If you go two days and have two people you can make two separate reservations and easily use two different coupons and only spend about 50$ per night. Both gift certificates are good for food/golf/accomodations so if you wanted to buy extra for food then even better.
I must mention that although i've never stayed here I've heard good things but this hotel is pretty far off from the rest of the touristy things in waikiki
I might be worth calling and double checking or getting something in writing before you commit $$$ to this though.