Hi, lottiedotty,
Just to let you know you are not alone with this problem. To date I have never had a problem with them in my collection ( 300ish ) of potted Hostas. However they decimate my heucheras and fuchsias every year. I am going to drench all the pots with Provado which is the only allowable pesticide here in the UK which purports to help control the problem. I am sure you must have used it and as you rightly say it costs a fortune. I am going to try drenching every three months to see if this works. The only other solution is to try a get the adults before they lay their eggs in the soil/compost and that requires inspecting the plants regularly and picking them off by hand. So I can't offer anything more helpful but at least you are not the only one suffering from these pests.
Dave.

I am going to try drenching every three months to see if this works.

==>>> is that according to the label????

ken