I have some harbor freight ramps, the basic ones that didn't even come with safety chains, that I got for like 35. I just use them for my snowblower, and haven't found a need for the safety chains, they anchor into pavement just fine, and have never even come close to slipping.
You just gotta make sure that the weight of the ramps can handle the weight of the mower. Don't get the trifold aluminum ones, get the basic ones I have and make safety chains yourself, or you can put plywood on it and make a nice wide ramp (snowblower wouldn't do well with this, but fine for a mower). The trifold has too big of spaces and it'll be hard to get your mower up it.
The only issue with ramps on a truck is they're STEEP. Its not easy maneuvering equipment up it.