I saw an offer from WebAuthorities a while ago on WHT, and they offered Plesk keys at reduced prices. Also they offered the option to get your own key by paying monthly.
For example 600$ one-time fee for Plesk Unlimited (I own the key) or 60$/mth, a whole year long (at the end you own the key, but during the year you're paying, you can also use it), so 720$ in total.

Now I mailed them and asked if they still have the monthly payment option available, but they don't. :(
So I was wondering if there was any other company that offers this... Please reply if you know any.
Companies may also contact me by e-mail or PM.

Thanks :)

As a follow up to help you out. WebAuthorities will offer them again, just right now our hands are full with several server orders.

As for a company who does leasing of keys outside the network (you lease to own), from what Plesk told me, no one does (but that was about 3 weeks ago so maybe someone does now).

If you want to do a shorter duration lease (6 months or less) I can work a deal out with you, just shoot me an e-mail.

Thanks Mike, I'll keep that in mind. :)