Be positive that you know the year, make, and model of your vehicle. For example, this could be - 2001, Chevrolet, Malibu. If you search online for cheap rims you will type in this information yourself, and if you go into a tire and rim store you will give this information to the sales rep and they will look up rim choices for you. This is important because certain rims will not fit on certain cars, and if you are looking to upgrade to larger rims they may rub or bind if they are too big.
Search the internet first for cheap rims. There are numerous websites like tire rack, and discount tire that sell cheap rims online. It is a good idea to start with a web search because then you have a basic idea of what rims prices are, and different rim sizes available for your car. Many web sites that sell rims offer special sales and discounts that are only available by placing your order online. You can either have your rims shipped to you, or they will give you the option of picking an affiliate shop - then all you do is go to the shop and they install your rims there, whichever is more convenient. Buying cheap rims online is also helpful for people that are intimidated by the in person negotiations, hassling sales pitches, or just want to have everything already set up.
Don't forget about eBay and Craigslist. Ebay is an excellent place to buy cheap rims, and you can often win brand new rims in an auction for a price much lower than you can buy them in the store. Craigslist is another great place to look, and if you can bring cash and negotiate in person you can often get the cheapest rim prices of anywhere. Never underestimate the power of a cash deal in person. Once people see dollar bills they are likely to become a very motivated seller all of the sudden. The only drawback to these methods is that you will not get the support of a business or company behind the sale, and you will be responsible for finding someone to install them, as well as making sure they will fit. Many times people on these sites are selling brand new rims because they spent too much money and something came up now where they need it back, and you can capitalize on this opportunity.
Search locally for cheap rims, then match up local rim prices to the ones you found online. Looking in the tires section of your local yellow pages is a great place to find shops that sell them. Places that sell tires often sell rims, and they regularly send out flyers in the local newspaper with their current sales, especially in the Sunday paper.
Don't be scared to negotiate for cheap rims. This can't be overstated. Most if not all of the people who sell rims and tires are on some type of commission or incentive program. They are fast talkers and smooth operators who want to wrap up a sale at all costs, and they have room to come down on the prices and installation fees. Use this to your advantage and present the prices you found online in your negotiation. Most stores that you will go to in person match prices as well, it may even be part or their policy but you have to ask because many stores won't tell you this up front. Matched prices = less commision for the salesperson.
Don't pay for any extra services and warranties. The rims are warrantied by the manufacturer against factory defect and being warped or bent - that is all you need. Any kind of oil change package or car maintenance program they might offer you is only to make the salesperson a dual commission and make the shop more money. All that does is drive up the price of your cheap rims making them less cheap in a hurry.