Here lies the problem. Trademarking or copyrighting something is a few hundred dollars. The big problem is defending it. If someone decides they want to challenge your mark or release something similar, will you have the capital to defend your idea?
To put the kibosh on some misinformation here:
1. Defending your IPs here isn't actually a "big problem" given the fee shifting provisions under the Copyright Act and the Lanham Act.
2. Copyright protection is free - it attaches as soon as create whatever it is you've created. Copyright
registration is $30-50 depending on what you're registering and how you file. You want to register so that you can take the action to Fed. Court to defend your creation if someone infringes it. Registration also provides for statutory damages, so you don't have to prove actual damages.
3. Trademarks are protected by common law, state law and federal law and there are different mechanisms operating at each step. Yes, it's more complicated (and expensive) than registering a copyright, and you will forfeit your application fee if you do it wrong. If you want to pay a professional (like me) to do it, you can expect 3-6 hours of work to vet your mark and submit your application. It will cost more to register a logo than it does to register a "text-only" mark because the database is more difficult to search.
4. If you're talking T-Shirts, you may be require TM, Copyright protection or both, depending on the sort of design you're considering, how you're gonna market your products, and what the IP "landscape" looks like after you've done some preliminary research.
Also, the best approach here, IMO, is to hire a professional not to file these things for you, but to teach you to do it yourself.
"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime." -accredited to Lao Tzu, I think.