The therma pen and other higher end options work great, but you can pick up a digital instaread therm for like $10 at your local cooking supply, grilling or hardware store. I have a thermapen now, but used to use the cheap-o ones and just throw them away when they crapped out.
I dont understand the aversion to an instaread. Its called that bc its instant.
Yes, I can cook steaks to temp without it, but it takes two seconds, and it will help you cook a better steak. I dont cook the same strips or filets or whatever from the same store everytime, even if you are an 'expert' or just a 'redneck with a weber that's done it a few times', lots of variables like fat content marinade, cut whatever can throw off your instinct or normal read. Why cook a steak to 138 when you could have pulled it at 129?