Can you do it? can you get used to it? I cannot afford backing, and sheets are very easy to get.
Thank you for all of your comments in advance.

I have heard they are hard to hand quilt.

I did a queen sized one hand quilted, using beeswax to coat thread, had no trouble till needles were dull. I tried using them toooooo long. But I used a 200 thread count sheet, and it is good. The print and color matched enough, that I did a mock binding with the sheet to the front of the quilt. I am pleased with it, I used betweens needles( I tip I learned from here.)

I use a 200 thread count amd i have no problem if you use a higher count that mean the thread in the sheet is woven close and it will be harder to pull a needle through so if i was you i would use a 200 count

I hand quilt my quilts and use sheets for the large quilts I also use 200 thread count, I get them from Walmart. I have not had any problems. I have more trouble with something like a white on white pattern. I love the way they turn out.

I have read that sheets are easier to hand quilt if you wash them first to get rid of all the finishes that stiffen them. Makes the sheets softer.

If you are going to use a sheet make sure it is no closer a thread count than 200. You could also use a flannel sheet. I recommend washing it first as they do shrink.

how can I tell? There is a goodwill that I go to occasionally that has sheets, 4$ for a queen, 5 for a king.

It's always a good idea to wash new fabric before using it.

If you use sheets that the weave looks approximately like the quilting fabrics you used for the top, that would probably work.

It's truly amazing how much EASIER it is to quilt with a sharp (as in "new") needle!!!!!!!! I've used mine too long, also.

Same for a sewing machine needle.

Take a needle or even better a saftey pin with you to good will and try it on the sheet if it goes in easily that sheet should work.