There’s not a lot out there in a single fixture for $300. And the lights I would recommend for a 4x4 scrog are going to start at well over twice that. I know of one off the top of my head that would do a decent job in a 3x3 scrog type grow for about $360.
The only problem with that is that it’s a square fixture, and not easily added to later. 3 42" bars between 200-300 watts of cobs would be good. I think you could start with 1 for around $300, would be just a little shy of doing half that size. And then add another down the road, and see where you’re at then.
Otherwise you’ll probably be looking at 4 $80 fixtures from amazon/ebay. In my opinion, that will still leave a lot to be desired.
When running a scrog you don’t need quite the intensity as just letting them grow natural, but you want good relatively even coverage. And it takes a fairly large fixture to provide that kind of coverage. I like using something like cobs when trying to achieve this at lower cost, because you can run them higher and spread out the intensity without getting fluffy buds. But that’s just me. They cost a little more per watt, but you’re also getting more par per watt. So running a full 50 watts per square foot isn’t necessary.
Up to you, I know what it’s like to be on a budget. But I’ve also spent more money buying stuff 2 or 3 times because I pinched a couple pennies in the beginning.
Let me know what you think is the best option for you, and I’ll see what I can up with…