Koros, welcome to the board.
First: ATW will very likely index your site for free, regardless if you paid for one page.
That is assuming you have a site they feel worthwile indexing, which is mostly a question of having links to the site.
Paying for PFI does the following:
- instant access
- constant refreshing
IMO it's not a good idea to pay just to get in. It can make sense to pay for pages which are often refreshed, or for pages which might not make it in otherwise.
I would however not pay for an index page.
You might consider changing the url (you are allowed to change as oftn as you wish) to a page specially set up for this purpose, perhaps a page leading to your most important offer.