My friend researched various lock boxes but wasn't sure if the signal would get dampened or the heat / lack of ventilation might be a problem. 

Because of small life choices like that and learning those things early on, it's allowed me to see that I'd rather put the money I would have spent toward a car back into investments so I could buy 10 4Runners if I wanted to (which I won't lol).

The buyer spent over a year renovating it and it now has a market value of less than $250,000.

I'm not familiar with the tax benefits, though I have spent a little bit of time studying up on it. 

I've spent the last year or so learning everything I can. 

Big box stores?

Overall, in your shoes, I would probably do this deal and if your goal is to get more property, I would save the excess cash flow and whatever you would have spent in rent for the next one.

If you mean labor you can hire without licensing, workers company, etc, then you can find them standing in front of any large box store, paint store, etc. but keep in mind that many of these tasks you mention require licensed contractors in many states (not all) and when it is required, skipping that is a risk you take.

It's a box that connects to pipes.

Shoe box of receipts.