No need for a realtor or lawyer to buy at auction. RE auctions I've been to(local, in person, not internet) usually call for 10-15% of the purchase price to be paid on the spot by the highest bidder. The auctioneer will always disclose all of the terms at the beginning of the auction, but it's typical for the closing to be set about 30 days from the auction date. You'd need to have the rest of the cash or arrange for financing by that date. Also, pay attention to whether it is an "absolute" auction, with no reserve price set by the sellers.
Most auction companies will require bidders to provide proof of funds or a letter of credit approval from a bank before they are given a bid ticket, similar to what might be provided if you were making an offer on a house offered for sale.
I'd recommend attending a few auctions to watch the action, first. But if you think there's any chance you'd want to have a shot at the property, you'll need to take your driver's license along with proof of funds or letter of credit to the auction (just in case those are asked for).
Also, MANY real estate auctions now include a 10% "buyers premium" that is tacked on to the final, highest bid. If your final bid is $40K, you've agreed to pay $44K for it. This is in addition to the commission (in my area, around 6%) that the sellers pays the auctioneer.
With all that said.... my personal experience has been: In the last several years, in the midwest, real estate auctions have become much more competitive. I no longer see property selling at auction for "rock-bottom prices". In fact, I'm finding that browsing FSBO and MLS listings is much more likely to land me a good deal than an auction. In fact.... if I were to want to sell my home, I'd list it first FSBO to try to avoid fees and commissions... but if it hadn't sold and I was in any kind of hurry to sell.... I'd list it for auction instead of listing with an agent. This would be especially true if I were forced to move and sell an empty house. Every month of paying utilities, taxes, insurance on an empty house adds up and you eat that cost no matter what.
If you go to an auction, and especially if you participate, you'll learn that auctions (especially where the big "real estate" item is concerned) are very personal, engaging experiences. The auctioneer will slow down, speed up based on the bids he's getting. The auctioneer has "handlers" that "work the crowd", standing right next to the active bidders to "feel them out" and entice them for a higher bid. If the price has stalled well below what he knows it's worth, the auctioneer will grind the auction to a halt and then inject a short speech, making the observation that "there are pickup trucks here worth more than the bid we've got on this house". He's naturally doing everything in his power to get a higher price and most of them are very good at it. Bidders often become emotional, competitive, and with all eyes on them and under pressure to make a decision in a short period of time, it's possible to let emotion overtake rational thinking. Auctioneers usually advertise extensively. They get the word out about their auctions with no reserve.... and even if there's not a big crowd, there are usually quite a few serious buyers present.
I'm not advising against buying at auction, but the environment is much different than making offers/counteroffers in a traditional sale. I'd just advise getting a feel for the action before jumping in.
The last auction I went to was for a house in blue-collar section of a small midwest city. I own a house just down the street from house at auction and I paid $40K for it (they were asking $45K). The place I own is solid and needed $0 in rehab or repair to rent out (for $625). The place at auction needed appliances and probably $6K - 8K in rehab to be ready to rent. Heading to the auction, I thought this place would sell for $28K - $32K (after 10% fee). In my mind I was prepared to pay $28K for it. Even with 8K rehab required, I thought it would do better than the place I already owned down the street. He tried to start the bidding at $30K and had to go all the way down to $6K to get his first bid. Then the bids got "stuck" for several minutes at $12K. Then they got up to $18K (my bid). I bet he held the bid there for 15 full minutes. Finally someone bid $19K and he got a few more bids. It slowed down again in the $24-$28K range (where I quit) again and the final bid wound up being $34.5K ($37950 after buyers premium). I don't think there is any way that house would have sold through an agent for that price. And if it did, it would have taken months to do it. It was an estate sale and I saw the sellers talking to the auctioneer afterwards. They were absolutely thrilled. I almost got a $30K house for $19800. Someone else wound up getting a $30K house for $37950. I think there 5 total bidders, including me. Only about 3 others there to watch. It was a rainy, dreary day. For nicer places and nicer weather there will be more people out just being nosy. Nearly everyone here was all business.