Landing pages are either
1: straight out for sales pages.
2: straight out CPC advertising pages.
3: a combination of the the two.
If you get a sale from 1 or 3 then you will most often pay a commission for the sale. Examples of this you can find at Sedo.com, Afternic.com and many others.
The type two pages are pretty rare these days as CPC on domains is very low and carry the risk of infringing on other parties IP. As such most sellers will forgo the CPC aspect and only go for the sales page. Both Sedo and Afternic lets you chose if you want to put ads on or not.
Usually no other fees are involved other than the sales commission. However a few places (Efty.com?) lets you buy the sales page template which you pay for upfront, but then you pay no commission on any sales.
Currently, using type 1 straight out for sales pages and was finally able to confirm, if a landing page offer is received and domain is sold, as result, my registrar doesn't charge a fee and/or commission; if I'm not selling the domain in their marketplace.
My service dnmanager.com has about 15,000 domains on it. It creates a landing/contact page for each of your domains and also can be used to check whois security and monitor uptime. Also a live chat feature if you want to talk with people visiting your sites. It has comprehensive stat tracking as well. There are no commission fees it's just a simple pay per month for however many domains you want to park.
However, as said above, you usually don't combine a for sale page with ppc. Places like sedo (although I would be wary about them), domainsponsor, and parkingcrew (if you get in) will allow you to park for ppc. The PPC market was very good in the early part of the century but nowadays unless you have a domain that already has a lot of focused traffic you're not going to benefit from 1c a month clicks. Sedo charge a percentage when you sell a domain via their site - I'm not sure about domainsponsor or the others.
An example of a Domain Crew parked page is silklanterns.com which has a buy this domain link on top. It will not charge any commissions, but the inquiry will come directly to you and the domain does earn a pay per click revenue. Voodoo's pages are similar but I find them to load real slow. Would you rather have Sedo's people responding to the inquiries with their negotiating skills, or would you want to do it yourself and not pay a commission? That is the question in my mind.