Glad to see you have joined the forum! Yes, there are a lot of t-slot companies out there. Have a look at our blog article T-Slot: What’s in a Name to understand better who makes what.
As for choosing someone, we recommend looking around for not just the best price—which is important— but look for overall service, delivery time, and most importantly, policies on minimum order requirements.
Everyone has their favorite company, so check them out for yourself and see who will best serve you. You’ll notice on the home page we have a list of companies that have been in the t-slot business for years.
If I can help further, just let me know!