Hello, some people on this forum give good advice and are happy to do so. You haven't given enough information to get a worth answer. "Nice bike" is such a subjective term, for some, that means $4,000 bucks, for others, $200.
Here are some questions for you:
What will be the primary use for the bike? Casual strolls, long rides, fast riding?
What type of bike do you intend on getting? A Road bike, Mountain bike, Hybrid, Cruiser,etc....?
If you want a quality Road bike,200-300 isn't going to be enough. You can probably find one for that price, but it may not last you very long. Your looking at 600-700 for a bare bones entry level road bike. If thats the route you want to take, look into buying a used one from a reputable bike shop.
200-300 isn't quite enough for a quality new Mountain Bike either. 400-500 seems like the price for entry level Mountain Bikes. Again, try to buy used from a shop.
If you're looking for a bike to do casual low mileage strolls, 200-300 is a reasonable amount. Look at what your shop has to offer. Whatever you do, don't get a department store bike. These bikes aren't made to last and are put together by unqualified people for the most part. I wouldn't want to put bet myeline on one of these.