First post here, but I've been internet marketing for a couple of years and I have a basic level of experience...
If you want your product to be successful, you must be actively building an army of affiliates. Affiliates aren't going to come crawling after your product unless you give them a reason to promote. This is especially true with the big fish, since they typically only promote what will make them a lot of money.
It will be very, very, difficult to create a successful product on Clickbank unless you have an active army of affiliates promoting or your own untapped traffic sources that you're using to make sales yourself.
But if you're looking to build a huge army of affiliates...
You have to give them a REASON to promote.
There are already thousands of products in the Clickbank marketplace, so what's gonna separate yours from the rest? It all boils down to a few basic principles...
(a) Provide tools for your affiliates - This makes their life much easier and it makes your product seem much more attractive to them. When all affiliates have to do is visit your affiliate page and use some of the tools there, they'll be much more likely to promote. Coffee Shop Millionaire is a very successful product on Clickbank and they have a full blown affiliate center you can check out at affiliates.coffeeshopmillionaire.com as an example. If you have a WordPress blog, you can install a free plugin called 'WordPress Affiliate Resources Page' to create your own affiliate center (search for it on Google).
Provide banner ads, email swipes, solo ads, PPC ads, blog articles, and anything else you think would make your affiliates lives easier.
(b) High Average Sale - You mentioned above that you're offering 50% commission. This would not necessarily be a bad thing if you were selling your product for more, but considering that Clickbank takes 7.5% of the sale + $1 it really boils down to less than that, which will turn a lot of affiliates off in the beginning.
Because you're only charging $30 for your eBook, offer 75% commission. Then, add some upsells in the backend and maybe even some recurring commissions to increase your average sale and attract more affiliates. You tell me... if a super affiliate has a choice to promote a product with or without upsells and recurring billing, which are they most likely to promote? Not to mention, most super affiliates (the affiliates that will make about 98% of your sales) will only promote a product if they can make a decent amount of money off it and by adding recurring billing/upsells and increasing your commission rate to 75% you're making your product look much more attractive to a lot of affiliates right off the bat.
(c) Product description geared towards affiliates, not customers - This is a HUGE mistake most Clickbank product vendors make. How many customers actually go into the Clickbank marketplace and buy a product directly? Not that many. Now how many affiliates are actively searching for products to promote in the Clickbank marketplace? A LOT more.
You need to gear your product description towards affiliates, explaining why they should promote and how it would benefit them. Provide a link in your product description back to your affiliate tools. Explain to them how you offer high commission rates, your product converts like crazy and how it will make them rich and successful. If you look at the top products on Clickbank, almost all of them have descriptions geared towards affiliates, not customers.