About low budget, are you talking about Stormtrooper costume?
If its Stormtrooper maybe you can do the research here first:
How much does a suit of TK armor cost? https://www.whitearmor.net/forum/topic/28304-how-much-can-i-realistically-expect-to-pay-to-finish-my-stormtrooper-costume/
I don't know about installment payment, but you can do the research and make a plan whatever you comfort and fit in your budget.
The main parts and most costly will be hard parts, the armor, You can check and contact the maker, Where do I buy armor? https://www.whitearmor.net/forum/topic/11538-the-various-types-of-armor-and-where-to-find-them/
Or you can start planning buy the softparts first.
Also you can contact Italica Garrison member for more information, there is an Attache in Italy, Davide @lorddavids