That is the biggest thing that is "irking me," people think that because I bought 27 sites for $2,500 that the websites are such low quality and useless! Why?
First, I hope your new business endeavor works out for you, congrats on trying something new.
As to my thoughts on why people have the impression they do, this is why:
First and foremost putting aside the cost/revenue side of things, 27 sites for $2500 meant the setup and labor expenses spent to break even on building them was less than $100. That's a tiny amount, and that's what gives the impression that the sites are not of great quality. I'm not saying the ARE low quality (haven't seen them)...just that assuming someone values their web development time at a reasonable rate ($25/hour?), that amount of labor expense is a few hours at most on each website, not a ton to develop high quality websites. But I don't know the full story...perhaps they were developed by an Indonesian web developer for vastly lower labor costs than what would be typical for American rates.
Going to the cost/revenue, not to be a buzzkill its skeptical someone would sell a business that pulls in 50k year for 5% of it's yearly revenue. If you talked to the owners did you ask them why they would sell the sites if they were raking it in? Did the reason make sense? It's not common for any legit business to sell for less than a year of it's profits, if it will be a perpetual ongoing business.
Unless the $138/day you note is the gross, and the expenses of the sites cost something hefty so the actual profit is much smaller (hosting, site registration, whatever? i'm not a tech guy so i don't know what would be involved), I either don't see how it makes sense, or you got a great deal. Alternatively, I don't know what the websites are, but if the $138 is dependent on a lot of fresh new content to drive the required traffic level to make that much, I may see how it makes more sense...the ammt of labor involved would probably be quite large for that many websites so it is either a huge time commitment and the 50k is a 'wage', or you'd have to pay someone to do content and the expenses will be large.
If I had to guess, I would probably lean more toward the revenue will be nowhere near $138/day, even gross.
Good luck! Once you start getting some real revenue numbers let us know how it's working out!