Hello. You did not state what country you live in. I hope it is America, because otherwise my answer may not apply.
I had this issue too when I started wearing hijab a couple of years ago. It's really not as hard as you might think to find modest clothing. You just need to shop around. Maxi skirts are fashionable nowadays, so you can find those in just about any store you go to, and many of them are pretty cheap. Many stores have their winter clothes on clearance now, so you should be able to find some long-sleeved shirts for pretty cheap as well. Be sure to get all cotton shirts, as you will want those for summer. I bought some cotton shirts from Kohl's about a month ago, and they were all on clearance at around $5. Since you need cheap stuff, look at discount stores like Ross, TJ Max, Burlington CF, and Value City. You should also try looking at thrift stores, flea markets, and yard sales. I have found lots of great stuff at those, most of which was like 50 cents.
Perhaps one problem is that you are looking for Islamic clothing. Islamic clothing is Arab cultural clothing, and frankly, I don't think you need to look like an Arab to be modest. You can wear western clothing and be modest, you just might need to adapt it a bit. For example, if you have some tight shirts, you could wear a sweater or shawl over it. For short sleeved shirts, you can wear a long-sleeved shirt underneath it. I have some thin white shirts for this purpose. If you have any summery maxi dresses that have immodest tops, all you need do is to throw a long-sleeved shirt on over it. And as a side note, many summer maxis dresses are made of rather thin materials, many of which are totally see-through. You should either avoid those completely or just layer it with a slip or another skirt, like how women used to wear petticoats. (The real kind, not those short, frilly, tutu-esque monstrosities you see nowadays.) I know you said you already have hijabs, but the same principle applies to those. Most stores sell "fashion scarves", many of which can be used as hijabs. Some of them are rather see-through, but you can always layer those. Just don't layer scarves in the summer, believe me. In the summer you want natural fabrics, like cotton, and you only want one layer on your neck. Anything more and you will be sweating profusely.
I hope this helped. Good luck.
Hi - people would appreciate you more if you adapted to local customs, especially considering your stay of one year. It shows respect and gains respect.
The way women dress in India -- sarees are still very popular, worn by a majority of women for all occasions. Worn well, these can be very elegant and attractive.
Younger girls, especially, college students, tend to wear western clothing these days in the four main metros but, by and large, a lot of women wear the comfortable salwar-kameez or churidars. These can range from elegant cool cotton outfits (sensible everyday wear for a hot climate ! ) to vibrant silks and fancy trendy evening wear. then, further, to jazzy, dazzling, elaborate party wear type stuff that can set you back a few hundred dollars each..
There are good outlets in the metros where you can get these pre-made or, you can have them custom-made by good tailors -- the salwars/churidars are sold as "sets" (stitched or unstitched) and available everywhere. If you mention the city you'll be in, readers can provide recommendations to good shopping areas/shops.
All the best and enjoy your stay.