Tenants file for bankruptcy

I bought a property at TS two years ago and inherited the tenants. We are on month-to-month lease now. They paid on time until May. They started to pay in pieces. I served them 3-day notice to pay rent or quit yesterday. They told me they will go see a bankruptcy lawyer on coming Tuesday. I know there is a new law protecting landlord if you have a judgment in hand from eviction court. But if you just file for the eviction, you still have to find a lawyer to file Relief from Stay to take your property out of the automatic stay. Someone quoted me $1800 for filing the Relief from Stay. Is that reasonable? I heard that bankruptcy only protect debtor up to the date of their bankruptcy filing (let's say Aug 30). They are still responsible for debt incurred after the filing. So if they don't pay me after Sep 1, I can start 2nd eviction on Sep 2. My eviction cost is cheaper than $1800. Any thoughts?
You advice is highly appreciated.
Bill