Encouraging people to start vintage racing with a big bore car, unless they are experienced racers, is just a bad idea. Too much horsepower, a lot of testosterone in the big bore groups, more risk. Formula Ford is a great way to go, as someone suggested, though less margin for error in open wheel cars, or you can readily buy an MGB, a Triumph and many other small and medium bore cars for $20k or less. Less hazard, good place to learn, cheaper tires and just about everything else.
Someone should let the newbies know what the whole picture is. So you've got a car, now you need a trailer and something to tow it with. Can't tow a corvette and suitable trailer with that mid-size SUV. Driver's suit, helmet, gloves, shoes, hans, another $2k easy. Tools, spares, just tires for that corvette may cost you $1500 for a couple of weekends. I figure every weekend I race my Triumph GT6 is $1500 for entry fees, travel/gas, race gas, motel, food and I haven't even touched the car. The car costs me another $3-$10k a year, depending on whether it's an engine rebuild year and what else breaks. Oh, and hundreds of hours at home in the garage to race six weekends a year.
OK, so I'm not complaining, just being realistic. I love it, live, live, live for those weekends, for the racing, for the friends, love most of my garage time - it's just the best thing ever (though by the tenth time you rebuild your brake calipers, the novelty has worn off). However, it requires commitment. If you don't commit and prepare, you get to the track, your car breaks, or you are one of those drivers that races once a year in a slow car and is, frankly, a hazard.
OK, off my soapbox now.