$30k is a lot to pay for that unless that included some major repairs (re-plumbing, etc.)In the future - you may want to consider buying materials yourself. 

Plumbing has been redone, it's all pex and the sewer line is pvc.

@Steve Mandelbaum He is saying that he does everything except mechanical, electrical and plumbing...MEP

Hydro Plumbing, Grand Electric, Jack Hammer Plus for fences and clearing out trees or undergrowth.

This is a substantial savings especially if you know how to do the framing, electrical, plumbing, roofing, ect. 

Bid after bid is too high but now I am looking to see if I can do the plumbing myself and hire someone to do the rest of the work.Who thinks this is an easy job?

I would talk to a head building inspector and/or a head plumbing Inspector and ask what TO watch for and what is typical when it comes up when that making an inspection and the  typical  common problems. 

It really stinks when you buy a property at market value, thinking it'll cash flow only to find out that the plumbing isn't up to par, that the water heater is going out, and that the oven is a relic from the late 70's. 

For my area you really start to get more issues in the 1940s where you have things like knob and tube wiring or non-copper plumbing that needs to be replaced. 

How didn’t the inspector look under the sink to check the plumbing or notice the cuts in the floor for the french drain stop and then pick up on the other side of the the basement?