The thing is, though, that many modern startups don't make a distinction between doing an integration and writing software.
It sounds like OP did the former, which means there's not likely an original product to sell, just a custom assembly of other products that form a system. That's a worthwhile thing to build and can be a money maker, but it's not an asset itself.
If you take away the installs of the products that make up your solution, then look at what's left... that's the asset that's being offered to OP. It might be something worthwhile, but most likely he's being offered it because he has an emotional attachment to what he's built, and they think he will take it without looking too closely.
It sounds like OP did the former, which means there's not likely an original product to sell, just a custom assembly of other products that form a system. That's a worthwhile thing to build and can be a money maker, but it's not an asset itself.
If you take away the installs of the products that make up your solution, then look at what's left... that's the asset that's being offered to OP. It might be something worthwhile, but most likely he's being offered it because he has an emotional attachment to what he's built, and they think he will take it without looking too closely.