That’s kind of a vague question to answer specially. It really depends on what you’re going to be doing with the whip, how much you want to spend, what kind of whip you want and how interested you are in whip cracking.
I usually like to recommend a 6 or 8 ft, 12 plait bullwhip for general whip cracking, made by any one of a handful of respected/recognized whipmakers (several of them are members here) as a first whip. That’s my ideal whip and I consider them worth the prices they command. A good whip will make whip cracking more enjoyable and you wont usually go wrong with a bullwhip from someone like Adam Winrich, Joe Strain, Paul Nolan, or Simon Martin, ect however if your not sure you want to invest $300 to $500 in something that you just have a general passing interest in, then that’s understandable too, there are other alternatives. I don't want to see someone, not be able to participate just because they can't always afford a higher end whip, There are still many decent quality professional whips available for around a $100 to $200 that are just fine and work great as either an Intro whip or for some one just some one just getting interested in whip cracking.
The best advice I can give is to search around, and try to get the best quality whip for what you can afford and that fit with what you want to do with it. Start by searching though this site, check out some threads like
viewtopic.php?t=19291
You will find that whip cracking is a very individual sport, so we all have are preferences, we can recommend whip makers and say this whip is good or not and why, but its up to you to do the legwork to figure out what is going to fit best for you and in your budget. Talk to these some of these whip makers directly, Your not under any obligation to buy and still all of them that I know are usually more then willing to bend over backwards (with in reason of course) to help a newbie or even an old pro out to match him or her with a quality whip that will fit their needs and budget.
There are also some cheepies out there though that are just a waste of money, but if you just want a wall hanger or a prop whip, a $20 or $30 Mexican bullwhip off eBay might have its appeal.
Dan