really looking to get new rims

so i have come to a decision to get new rims---for real this time. i want to drop to a 18 preferably but 17's will do if the deal is right. i want to get rid of the 20's for around 500ish with tire and new balance and hubcentric rings. i have the stock steel 16's with hubcaps for winter so this is no rush but if anyone has extra rims and tires sitting around that they want to sell or trade let me know. i am open to all GOOD offers.