tttokzy :
Nothing crazy expensive, just a solid ddr3 motherboard around around 50-100 USD
You already have the CPU + RAM? If not, $50+ on a 1st Gen capable motherboard is a waste, honestly.
Judging from eBay prices, an i5-760 sells for ~$25 USD, $50-$100 for a motherboard and probably $30-$50 for 8GB of used DDR3, that's right around $200 on the upper end.
Considering then, bundles like an i7-3770, compatible MB etc have sold for ~$150 recently (+RAM), you'd be in for similar money & have a substantially better platform.
Even in the $200 range, a modern platform such as:
PCPartPicker part list /
Price breakdown by merchant
CPU: AMD - Ryzen 3 2200G 3.5GHz Quad-Core Processor ($98.89 @ Amazon)
Motherboard: Biostar - B450MHC Micro ATX AM4 Motherboard ($51.98 @ Newegg Business)
Memory: G.Skill - Ripjaws V Series 8GB (2 x 4GB) DDR4-2666 Memory ($69.99 @ Newegg)
Total: $220.86
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-09-13 11:43 EDT-0400
Would net you stronger performance (depending on the proposed workload), and even give you decent gaming performance on the iGP front - negating the need (somewhat) to spend money on the 750TI.
tttokzy :
Technically I dont even have a budget, I buy 1 part 3-5 weeks apart from eachother, still being in high school and not having any actual job + living in Croatia where everything PC wise is crazy expensive. But regarding your question, I have a "budget" of 50 -100 USD per part. So if I have to upgrade my motherbaord, I also need to get a new set of DDR3 RAM, which i repeat, is crazy expensive in Croatia. So eBay is my go to I guess.
I would highly recommend saving the money up, then buying at once.
You've no way to test a component waiting a month in between and, especially in used hardware, if it's defective, by the time you know, you'll be well past any return period (if any exists)