They should not have increased in price, In early 2020, I and a partner imported 328 zebras from a well respected breeding operation in Indonesia. 278 of the were 1.5 inches and 50 were almost 2 inches. What we paid for the fish was $32 for the smaller and $70 for the bigger ones. However, there were box charges, clearing charges and shipping charges, So the ultimate cost of the fish landed in the states was ultimately $37.151 and $75.157 per fish. The sellers have a bagging machine and the fish were packed 1/bag.
Prices are now lower for the same fish.
My advice then would be you for not to add new fish gradually but to wait to get more until you can afford to buy them all at once. That way you will only have to deal with the pecking order disputes one more time. If your current six begin spawning before then, you might consider making a second group instead of putting the new ones in with the established group.
I bought several kilos of the Ebo-Aqiaristik food directly from them in Jan. of last year.
One kilo each of the Softgran Insect and Mussel.
One kilo each of the Shrimp and Veggie Sticks.
75 gm of the Artemia SuperSoft Granules (great for fry asnd other small mouthed, fish which need meat in their diet).
Total about 9 pounds US.
I am down sizing and have since sold all of my breeding groups of Hypancistrus since then save one, the WC 173. I am now almost out of the Mussel and Shrimp and getting low on the rest. The cost to get the stuff in smaller amounts from sellers in the states is pretty pricey though.
Zebras do need some veggies, but this need is greatest when they are young. I also feed a lot of frozen foods to my breeders and kids. For breeding, live is best, but I do not do live for a few reasons. Frozen is the next best option to live, imo. I am also a big user of the Repashy Gel foods. I use the Bottom Scratcher, Spawn & Grow and Spoilent Green. I mix each of the first two 80/20% with the 20% being the Soilent Green. I also use the soilent green on its own for the few ancistrus I have. But I also found that corys I have seem to eat is as well.