they won’t refund you any money and you’ll need to exit after 60 days or pay extra 1900 baht to extend for another 30 days. After that you need to get out.
That visa is useless in your case. It’s more if you frequently go in/out of Thailand like ever 7-10 days
since OP doesn’t know expenses of service providers he can only drop random number that would either be underpayment and driver will quote him correct higher amount or he’ll overpay if he offer too much as none driver would tell him that’s too much. I’ll take less.
So what’s point of him offering XY money instead drivers quoting him whatever amount they found enough