I have quite some experience when it comes to domain parking.
I find that a good way to invest your money is to buy or even register revenue domains.
You get them for around a 12 revenue months multiple for trademark typo's like:
www.wwwmicrosoft*com

The return is good but there is always the risk of a C & D letter. I recommend using private whois from Moniker.com and to just ignore those letters, a lot of times nothing will happen. In worst case scenario they'll take the domain from you but you'll have at least delayed it and most likely earned your money back already.
It's recommend to not spent al your money on 1 trademarked typo domain but spread the risk.

For generic domains that recieve natural type-in traffic you'll have to pay big bucks if you buy from resellers.
Since these domains have generic value and recieve an 'endless' stream of revenue you'll end up paying 7 years+ for good ones. So it's worth it to look for good deals and contact owners by whois who aren't monetizing their generic domains.

I mainly use Parked.com , domainsponsor and Sedo.com for domain parking. It's recommended to use the Google Keywords tool to select a high paying keyword matching your domains category: h**ps://adwords.google.com/select/KeywordToolExternal

If you need any more help feel free to ask, just sent me a pm.
I'm not sure if this is the info you were looking for or if you wanted to know more bh stuff regarding this subject. To be honest I dont have experience with that.

Usefull resources: dnforum*com, namepros*com, , dnjournal*com,