Most important? Realize almost nobody is that amazingly more intelligent / driven / insightful / etc that you can't achieve similar results.
You could try Open Cart, it's quite a modern PHP cart with paypal etc built in.
We read in a lot of places about getting "traction" before speaking with investors, but have never really understood at what level this means. Ie- 100 or 100,000 users? - 1,000 free users or 10 paying ones? - high conversion rate or repeat visits?I realize every startup is different but would love to hear what figures you were getting when you / investors considered you had "traction".
Here are some tips: 1. Keep your costs very low while you are figuring out if there is a market. If possible, use sites like shopify, eBay, Amazon, etc to find some first buyers for minimal web development and only order a relatively small amount of inventory - hopefully you won't end up with a pile of un-saleable inventory while working out if this can sell.
2. If you can source the inventory cheaper than is the current market price, that can be a good advantage - but don't think that cost will be your only advantage without worrying about marketing etc.
3. When calculating your sale price, factor in fraud, refunds, wastage, etc. Regarding fraud, it seems like a regular occurence - be hesitant shipping large orders to unknown customers with unverifiable addresses.
Hope that helps.
BUT having re-read your post a few times, and obviously not being involved at all, I am not sure that Tanner is the malicious con man you make him out to be.
ie being a douche != a con man && things not working out != being manipulated.
For example: 1. Additional cut to Zen Club - Zen Club the company is separate to Tanner, the individual. If both are contributing to the App Company (eg you mention the brand, the photoshoot etc), then it seems reasonable to both to be part of the split. I agree that you should probably have negotiated both Tanner's and Zen Club's contributions together, but it seems irrelevant whether you split it as Tanner gets X% and Zen Club gets Y%, or Tanner gets (X + Y)% and Zen Club gets 0%.
2. "We started reporting to Tanner like a boss" and Ryan always agreeing with him. - These seem to be interpersonal dynamics that doesn't necessarily point to Tanner being a con man. I assume there was no backroom deal where Tanner paid Ryan $X to always agree with him etc, in which case Ryan made his own decisions which simply happened to disagree with you. Similarly if there were no deals that forced you to start "reporting" to Tanner, then it seems like everybody simply fell into this dynamic.
3. Invisible Lawyer and Boilerplate Contract - Did you ask to meet the lawyer? - The lawyer is presumably busy, and you mentioned he wasn't being paid for his services, so the fact that you got a fairly generic first draft and the whole process took a long time doesn't mean anybody was being malicious. Even in the best circumstances contracts take some time and always with multiple revisions first.
4. If the runway ran out you would have no income while Tanner still had his gym. - you not having an income if the runway runs out is a standard risk for founding a startup - yes Tanner still has his gym. He presumably spent some separate time and investment to set up and keep running, so this also doesn't sound malicious.
5. After you quit, domain / email / ftp accounts were changed - standard practice I would think
6. Ryan got 5% - I agree it does seem low, but it is possible this is a fair deal. Think of it this way - the investor put in $250K, Ryan did not put in any money, was working part-time, and none of the apps got approved into the app store (is that a technical responsibility?).
7. Other 'grievances' (eg drives BMW, not using real names, acting career, charging you for an 'overpriced' gym membership and DVD series, alcohol, charging for $30 pillows, 'squatting' in the spare office, etc) - apart from adding color to your story these details are irrelevant at best - at worst it makes Tanner a douche, or wasteful with money, but does not necessarily make him a con man
Obviously I don't know the full story so take what I wrote as you will. It just seems a shame if you take the belief that you were conned (and more importantly, take an overly-sceptical / distrusting view into your next project where it could become self-fulfilling) based on only 1 of several possible interpretations of what happened.
CJ mentioned above is the biggest but they tend to have restrictions like minimum traffic, sales, etc. Depending on where your traffic is, you can also try Clickbank, Clixgalore, Pepperjam, Zanox, to name a few.
Tip 1: be very sure how much each sale is worth to you, taking into account refunds, cost of sales, operations, etc. You don't want to be paying out more than your margin...
Tip 2: watch your cashflow. You don't want to pay out before you collect from your customers.
Good luck!