30% might work in software, but it's is a very deep discount for most physical retailers.
If the product has a 50% margin (sells for $100, costs $50 to source) then your retailer makes $100 for 5 orders instead of $50 for 1 order.
Except they're probably keeping their own inventory, so they now have to keep $250 of inventory for that $100 in profit, rather than $100. This is problematic because a lot of online retailers are limited by their working capital.
This is a drastically simplified example, but the bottom line is that physical retailers think very differently than software sellers.
Great idea for an app either way. I wish you the best of luck with it as you learn the territory. For something similar in the Amazon space (a platform that lends itself much less to split testing) check out splitly.com
Get yourself into a mastermind group with 2-5 others in a similar situation - solo founders, bootstrappers, etc. You can start with just 1 other person then add more.
Have a regular 1 hour video call every week or two. Everyone gives updates, support, and keeps each other accountable on goals.
Keep a Slack/Skype channel open in between to say hi, help each other, share wins, etc. Bonus points for meeting locally, but online is fine.
Why? Masterminds are the biggest thing I did going from wantreprenur to actually shipping & earning from products. They're also one of the best things you can do to beat entrepreneurial loneliness. Every week you meet other people who share your struggles and are invested in your success.
If you find at least 1 other person willing to do this (a few candidates on this thread already, or make a FB / LinkedIn post) I'll happily join the first one to facilitate & show how. Email in profile.
P.S. A coworking space + online communities like founder cafe, product people, complice, wip.chat (h/t other posters) can also be super helpful.
Somewhat related: There's a mastermind group that publishes their sessions as podcasts (and I think on youtube too), called the "entreprogrammers". Some time ago they started to organize spinoff groups, and are occasionally looking for new folks. Check out http://entreprogrammers.com/
One thing I like about listening to this is that you really hear about the struggles, not just the successes.
Create a study group or get yourself an accountability buddy or coach who you check in with on a weekly basis. Could even be a friend who's not involved but whom you commit to emailing every week with an update and a goal for next week (maybe give him $100 that he'll only return if you follow through emailing every week). You can also do this via a public study log - blog, forum, etc that you update weekly or daily. Nothing is as useful as a little external social pressure and support. This seems particularly relevant in your case since you say you've tried doing this on your own before. Then, I'd combine that with actually having your schedule for those 4 months worked out, know what has to be done by when. Best of luck.
Also - read the "War of Art" by Steven Pressfield. Excellent book about resistance to hitting our goals. Indecision is simply resistance against what you know you should be doing - flipping is easier than persevering. Get a routine, make a habit of it (eg: commit to study at least 20 mins at the start of each day and continue if you get in a flow), etc.
If the product has a 50% margin (sells for $100, costs $50 to source) then your retailer makes $100 for 5 orders instead of $50 for 1 order.
Except they're probably keeping their own inventory, so they now have to keep $250 of inventory for that $100 in profit, rather than $100. This is problematic because a lot of online retailers are limited by their working capital.
This is a drastically simplified example, but the bottom line is that physical retailers think very differently than software sellers.
Great idea for an app either way. I wish you the best of luck with it as you learn the territory. For something similar in the Amazon space (a platform that lends itself much less to split testing) check out splitly.com