Choosing the best ear phone in your budget is the thing you should do!
Now, first thing to do is set a budget! Then choose from where to buy!
I prefer online because you can choose from a variety of options and there are so many online stores these days! .
The next thing is go through a variety of ear phones and decide if you want a wired one or a bluetooth one based on your requirement like if you want one for gymming you cN go for a wireless bluetooth one and trust me you get really good earphones in reasonable prices.
You get amazing quality earphones on amazon and incase you have a lower budget but want a really really god one I would recommend aliexpress, ofcourse it is a Chinese product and it will come from china and the delivery time will be longer, but if you choose the rigjt one you get really really good ones like ipudis, baseus or kz zst( modular) which are phenomenal!
Im not supporting the Chinese economy or something, just suggesting as you get good products!
There are a certain things like battery , colour , waterproof and the model of the ear bud which you will have to look into while choosing a bluetooth earphone.
Good luck, get a good one!