Correct me if I'm wrong, but you state that earnings are about $1,900 per month at 10-20% ROI. So ROI per month is $190 to $380?
12 months ROI would be $2,280 to $4,560 if business is stable. That's a far cry from the $26.6k you're asking for. If you're willing to bring the price down by a lot, I'd be interested.
ROI is 20%-40% from what you invest in leads. Some leads can be sold for higher and some can be bought at a lower point. Either way, you profit.
If it's not valued at $26.6k, what would you value this business at? Usually businesses are valued at 12x-24x times the average monthly income.