I am looking to grow my own food like leafy greens and tomatoes, is there an online site where I can look at the different fertilizers they offer and order them? I cannot seem to find anything when searching, most require big orders and it looks like they are aimed for farmers.

Thanks.

Have you tried lazada? But the shipping costs rapidly increase, by more weight.

Usually any town or city has an agricultural store. Normally they also sell smaller sized packagings, that they repack by themselves from the wholesale 20 or 50 kg bags.

Home Pro or the likes also have standard chemical and organic fertilizer for sale in small sizes

For what it's worth: I started about a year ago to produce my own worm castings (on a small scale albeit). This (1) uses up food scraps and (2) produces some fertilizer for my potted plants. For the bigger plants/garden, I just use good old cow manure. Costs about THB 50/sack. I always leave it for a minimum of 6 months before applying to garden and grow beds.