There are several choices for inexpensive bidet attachments. The one I’ve used is the BioBidet Elite3, which honestly does a great job. It’s hard to get the front-to-back angle right, so the front of the toilet seat ends up slightly hitting the top rim of the bowl in my setup, but this isn’t a huge deal. Models vary in whether they have both front and back-directed washing and a couple of other features, so check the features you want.
The big luxury (and expense) of fancier bidets comes mainly from heating the water. In addition to the substantial price of the heated bidet, an electric outlet has to be run to the wall behind the toilet. So I use the BioBidet when my ridiculously expensive Toto Washlet is being repaired. The Washlet repair alone costs more than buying a couple of BioBidets. I really like the heated water and the heated seat, though.