Slice,
The Marchand is a good one for your application. You can buy it as a raw board, a kit, a semi-kit (where all the boards are assembled and tested -- you have to do the mechanical assembly and a little soldering), or as an assembled & tested unit. It is pretty good for a budget, op-amp based unit -- certainly better than the majority of the pro stuff that goes really cheap. I have one of the 2-ways that i built as a kit, and althou not the last word in transparency does the job until i can build my own.
Discreet devices are usually better, but not very available & certainly more expensive.
And there is the Marchand Tube XO -- it is quite expensive.
Being able to build your own, definitely puts a lot of flexibility into what you can do, and the place to start learning that is to buy one of John Pomann's
Active XO experimenters kit which has enuff bits & instructions to let you really learn & play.