Think like Disney does!
For most people their favorite is DESSERT!
So like a PP suggested - have a DESSERT PARTY!
You could easily do cookies, cakes, parfait cups, cobbler, pastries, and tons of other finger food desserts - along with a few types of punch - and then coffee - tea - and water - and call it a day!
When it comes to making it 'look good' think garnish - an elegant theme - some inexpensive flowers - rented table linens to dress it up - and make it look fantastic!
I bet your could do a very classy backyard reception for $250-$500 depending on what you do!
Depending on what their 'style' is - you could even do a pot luck - wish you luck - reception - and save your money to hire a small band!
We did a ho-down style rehearsal dinner and got ALL of our food from Wal-Mart! (Fried Chicken and all the fixins!)
We hired a bluegrass band - invited everyone we wanted to and started the part the night before! HAHA
We rented the dining hall at a local 4-H Camp - lit the path with very inexpensive luminaries - bought a few table decorations - a few bails of hay - a few pumpkins - and then moved ALL of that to the Church the next day.
So we got double duty out of our (inexpensive to start with) decorations!
We have a beautiful wedding - on a beautiful day! We

Fall!