Having purchased 12 Zebra plecos over the past 3 years, and losing three .... and not yet to have a successful spawn, I wouldn't recommend starting off with Zebra plecos.
Long fin albino bristlenose plecos tend to sell well.
Take a moment to put down all of the things involved with selling for profit, and I think you'll quickly realize that you won't make much.
I recommend that you do this for the love/fun of breeding, and if you want to sell, then think of the money as an offset to the cost, but you will unlikely make profit.
Here are some thoughts to get you started:
1. Shipping: Priority around $20, Express USPS around $60
2. Each fish would probably only sell for around $5, unless you ship breeding pairs. Breeding pairs tend to sell for a bit more. More fish = more weight = more shipping cost.
3. You'll need shipping bags and shipping boxes (with insulation)
4. Time, this is important. The time it takes to raise the fish, electricity, water changes, food, dechlorinator, time to catch the fish, bag them, box them, label the bags and box, and take them to ship.
5. The risk of losses in shipment (things that you have no control over, like lost packages, delayed packages)
If the process seems like something that wouldn't be torture, then I would encourage you to do it. I actually enjoy the process, but I've learned that it doesn't make you money.
I enjoy the fact that I have bred something that someone else wants. I take pride in packaging to make sure the fish arrive live and healthy. I also enjoy hearing about successful shipments and getting the compliments from a satisfied purchaser.
But, I don't do it as much as I used to, since I've realized the the time it takes removes any profitability from the activity.
Sorry for the buzzkill, trying to keep it real