NEW YORK (CNN/Money) - Web site entrepreneurs and auto industry executives have seen their big dreams of big auto sales on the Internet deflate faster than a slashed tire. But as a would-be auto buyer, you can get the best possible price on a new car by researching and maybe even buying online.

Contrary to the hype of a few years ago, online transactions today account for fewer than 5% of new car sales. But nearly two-thirds of new car buyers do research online before they start shopping. That's smart. For crucial price information, start looking at the cars you are considering under our Best Cars heading. You will get the list price (the manufacturer's suggested retail price) and the dealer's cost, or invoice price. You can get similar data and reviews at auto research sites like Edmunds.com, the Kelley Blue Book site, kbb.com, and CarPoint.msn.com.

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Focus on the invoice price as your starting point for a good deal. Supply and demand determine where a car is selling relative to that invoice number. For most cars your target price should be within a few hundred dollars of the dealer's invoice cost. (For especially hot-selling cars like the retro Ford Thunderbird, the rules are different, of course. They may be selling at full MSRP or even more).

In addition to the MSRP and invoice price, the Edmunds.com Web site gives you another, very valuable price number: the car's so-called true market value, or TMV. Edmunds develops the TMV number from supply and demand data on a given model and by spot-checking more than 400 dealers around the country. Edmunds also will factor in regional price differences once you enter your zip code. The regional factor can be important; the Lexus RX300 sport utility vehicle, for instance, recently was selling for a higher price in the Northeast than in California.

Valuable as it is, though, Edmunds' TMV is not the last word on your target price. It aims to be the average selling price. If you are a capable negotiator, you may well get a better deal. (Remember to add in all the options you want, keeping the same percentage margin over the option's invoice price as the TMV is over the base invoice price).

A second, though less comprehensive, source of target-price data is autoadvisor.com. For the models for which it has data, this site shows average transaction prices that are generally lower than Edmunds' TMV ($200 above invoice for a Honda Civic, for example, versus $700 over invoice quoted by Edmunds). The site is run by AutoAdvisor car-buying service, and its prices tend to be lower, in part because they factor in the deals closed by its professional negotiators for clients. (If having somebody shop for you sounds good, AutoAdvisor charges $227 for dealing entirely by e-mail, and higher prices for more service up to $437, including telephone advice on helping you choose the car, then negotiating the deal for you).

Armed with what is a realistic target price, you are ready to negotiate with various dealers to get the best price. For instance, software developer Byron Glueck of Charleston, S.C., found that car salesmen negotiated more seriously for a new Audi A4 Quattro after he showed them a printout of the Edmunds TMV price. He wound up getting the Audi $800 below the Edmunds price.

If visiting showrooms and sitting through lengthy negotiations sounds like just too much hassle, you may be among that 5% of buyers who are ready to buy online. There are drawbacks, but if it works for you it can be very, very easy. Internet services come in two varieties: referrals to dealers and direct online sales.

The biggest, best-known referral service is Autobytel.com. If you fill in the model you are looking for on its Web site, you will get a call or e-mail from a local dealer with an offer on price. The drawback is that the referral goes to just one dealer; with no competitive bidding. You aren't likely to get the lowest possible price that way. On the other hand, if your previous research shows the offer is a good one, you can have a new car in short order with very little hassle.

The last competitor still alive among direct Web sellers (the ones who don't refer to a regular old-fashioned auto dealership to close the deal) is CarsDirect.com. With CarsDirect, you can see immediately on its Web site what the price offer is for the car you want without ever actually communicating with anyone. In some cases, the offers are sweet indeed.

For instance, the CarsDirect price for a Toyota Camry LEV6 with standard features was just $200 over the invoice price, compared with the $700 over invoice quoted by AutoAdvisor and $1,500 over invoice quoted by Edmunds TMV. Such low prices are not true for all models, and CarsDirect -- which acquires its vehicles through dealers -- may not be able to come up with exactly the color you want. And it rarely can get the hottest-selling models at all.

But if you are flexible about color and options, the price and convenience are often hard to beat. Eileen Horwath, an analyst for a San Francisco consulting firm, had heard about CarsDirect from friends. She got a low bid on a new Honda Civic EX coupe and six days later had the black Civic delivered to her office.