I have two enormous windows (one is a bay) in our sitting room so curtains were a large outlay.
I bought readymade (dryclean only), lined curtains, stitching pairs together but have managed to wash them in a large drum commercial laundrette machine. They are a heavy cotton and did shrink about half an inch, so I was fortunate that shrinkage wasn't worse. I took a gamble. We don't smoke either but they (cream) do look overall grubby after a year or so.
I have been looking for 'washable' curtains for about a year, having redecorated but can't find anything I like. I would consider making them but now probably prefer readymade.
Incidentally, an advert has popped up in this thread, offering curtain material...£473 a metre anyone?
With our huge windows, we'd need a mortgage!