Just bought Evo 4G off craigslist. Few questions...

[TheLovatScout]

So I bought an Evo 4G off craigslist. I told him I just wanted a clean ESN and no water damage. I got it and won't activate it until my girlfriend comes back into town. But I did check one thing after I left. Bootloader. I noticed the Security was off (S-OFF). The HBOOT version was this:

SUPERSONIC EVT2-2 SHIP S-OFF
HBOOT-2.10.0001
MICROP-041f
TOUCH PANEL-ATMEL224_16ab
RADIO-2.15.00.11.19
Oct 15 2010, 12:07:00

Since I won't have it activated until around Thursday or Friday, I still have time to turn the security back on. And switching it back to S-ON is just relocking it, right? I'm sure there's a thread here that explains how to do so, so I'm not worried about that.

What I am worried about though, is why he sold it to me for $175. To me, thats cheap for the phone, it was in practically perfect condition and even came with an extended battery. Do you think he broke the 4G antenna? Is there a way to check that before bringing it into Sprint?

Also, I don't need to have mobile internet connection to turn S-ON, right, I can do it when it's still not activated...?

Any help would be very very much appreciated!!!