I understand the desire to do this, but I really recommend against self-catering. You have a pretty big guest list, and you're going to be working your own wedding (and likely asking for help from friends/family members). In addition to that, there are a lot of health concerns when it comes to making, storing, transporting, and serving that much food. I've been in the wedding industry long enough to here some unfortunate horror stories about illnesses at self-catered weddings.
Mexican and Italian food are some of the most cost-effective food types to get catered out there--you can definitely do it without breaking the bank. I highly recommend you look into local options.
My first husband and I did this. While the food was delicious and affordable, I would not recommend. My new husband spent most of our reception in the kitchen! My favorite song came on and I was livid he was no where to be found to dance with me. My cousin stepped in to save the da though and I’ll never forget that.. We did hire a couple friends of his from culinary school to help which was a good idea to help pull it off. If you can avoid self catering, definitely don’t do it.
My husband did this because we used his restaurant he works at as the catering. That being said, most of his time pre-ceremony was in the kitchen. We only had 30 people and it was a lot of work. I wouldn’t recommend it, but it can be done.
HIRE someone...please...it's going to be so much additional stress, mess, time management. If you want to cater something, maybe your rehearsal dinner? It just seems like a lot of additional pressure on y'all and not something I would wish on anyone.