Someone offered to buy my property before I put it on market

[Jeff West]

Hi BPers. I need some advice. I bought a foreclosure and just got the tenant out today. Out of the blue I got a visit from someone who happened to see an expired listing (pre-auction) and asked if it was for sale. When I told them it would be as soon as renovations were done they offered to buy it as is. The offer was pretty much what I would have netted discounting renovations and commissions, and if it's legit it would be great to get it sold quickly. So a couple of questions:

1. Does this sound fishy? They did show up right when I was finishing my cash for keys agreement and securing the property. (tenant was still in the driveway!) They say they love the area and the sister already lives in the community (gated)

2. Since I always use realtors and their title and escrow to handle transactions, how simple is handling it myself? Is there a good resource to research the process? This has potential to be a super quick flip, but I'd hate to slow the process with a misstep. 

Any responses would be greatly appreciated.