I don't mean to be an *** but if you can't afford a DOT, then maybe you should just find another job for a while and do that until you can afford to go on the road. We already have enough drivers who can barely afford anything like food while on the road.
Even though your new boss should pay for physical some employers don't so if you really want this job ask boss if he can pay for physical then take so much out of your checks till its paid for or ask a family member or friend for help.I don't know of any programs that'll help.
Why should they pay? I mean it isn't like a $800 for a dot, $50 to $75 is the norm and it is a part of your responsibility to maintain your CDL. the next thing people would expect is to have them pay for their renewal.