Build plugins or themes for WordPress. There are 58 million active WP sites now. There are mature markets for listing and promoting what you create. Bonus money if you can tie what you build into generating revenue for customers -- affiliate marketing tools/integrations, plugins or themes that play with existing e-commerce plugins or themes people use, marketing tools, etc. If you can do that, you can justify a $50-100 price tag, and just one sale a day will create the revenue you need.
8 years ago or so, I ran a little ecommerce site with a wholesale/drop-ship product provided by another company. When I needed extra spending money (being a full-time college student at a private university and no savings), I'd clone my own site. I'd design a new theme for the shopping cart software and sell the same product. I'd advertise it on Google AdWords for a few days to get some orders. Then I'd package that all up and list it on eBay -- a fully functional site with existing customers, a supplier, a known conversion rate, and pre-written ad copy and keyword list for the buyer. These days people use Flippa instead of eBay to sell websites, but it's something you could try as a web dev.
Question I've always had for WP Theme businesses: is there any need / common practice to prevent plugin piracy? Or is the market so big and pirates such a small portion of it that it isn't really something worth worrying about?
IMO, it would be counterproductive to employ any kind of obfuscation or license protection. Having access to the code is part of the reason people choose to build their sites on WordPress. More installs than not have some kind of customization done. Plus, you'll have less satisfied customers (inevitably a significant portion will have issues getting the loader/licensing setup to work on their shared host, or will have other issues you can't help them with because they can't debug the code) so less blog writeups / recommendations driving referral sales.
I was in the WP business for a while, with about a quarter million in sales before I sold it off, and did nothing to prevent piracy. It wasn't an issue. Someone pirating the code doesn't hurt me. Anyone that wanted the plugins/themes and had money was going to pay for it, as that's the only way they would get support and updates.
The people paying for your WordPress plugins and themes are, generally speaking, people who don't have time to fuck around with piracy.
I've experienced this first hand. As a junior web developer at an advertising company, there were plenty of times when my grand schemes for how we could do something for free on WordPress were met with "no, just pay for it".
Mostly echoing what others are saying here. When I deliver a wordpress site to a client, there is no way I am going to include pirated software. I don't want any sketchiness finding its way back to me. Also, I will pay for any software/plugin/theme that costs less than my time to build the same thing. It's just a matter of numbers. A $35 theme can get me 80% of the way to a client's desired layout. If I'm getting paid $500 for the project, then I'm making $465 for only a couple of hours of work, rather than $500 for several hours of work (starting from scratch).
It's like any other piracy as long as you take basic precautions you'll be fine. If you make something worth pirating generally it's worth buying, don't worry about the people who will never buy your product, worry about making the people who do buy it happy.
I'd recommend away from doing this … not because it's a bad idea, but basically because he's in a pinch and he doesn't know the space.
Plugins or themes could require a lot of trial and error before finding success, and buyers may not come until later. He needs the cash now, so he should go the sure thing and try to find paying customers directly rather than put things up for sale and wait for results that may never come.
8 years ago or so, I ran a little ecommerce site with a wholesale/drop-ship product provided by another company. When I needed extra spending money (being a full-time college student at a private university and no savings), I'd clone my own site. I'd design a new theme for the shopping cart software and sell the same product. I'd advertise it on Google AdWords for a few days to get some orders. Then I'd package that all up and list it on eBay -- a fully functional site with existing customers, a supplier, a known conversion rate, and pre-written ad copy and keyword list for the buyer. These days people use Flippa instead of eBay to sell websites, but it's something you could try as a web dev.