Usually the entry fee is between $100 and $1000, although there are satellites to these WSOP qualifiers.
WSOP qualifiers are done in three main ways. They are regular satellites, money-added satellites, and freerolls. The main satellite takes the amount of the player’s buy-ins and divides them to buy a World Series of Poker seat. For example, let’s say there are 110 people that play a $100-$10 WSOP qualifying tournament. In this situation there would be one seat awarded to the World Series of Poker and the additional 1,000 would be divided among the first few finishers after the winner. The super-satellite is the one you see for $10+$1 and then a seat is awarded to the $100-$10 WSOP qualifiers on a 1 for 10 basis. Some high-roller WSOP qualifiers might have just one table where the buy-in was $1000+$100 and then the winner of the table would get the WSOP seat.
Another type of satellite into the World Series of Poker is the tourney where there is no extra entry fee. They are few and far between now and look like this - $100 with no extra $10 charge. Sometimes you will see these WSOP qualifiers if the online poker room is guaranteeing a certain number of seats from the tournament. The online poker room may be doing this because they want as many people from their own site as possible to be playing in the World Series event, for publicity of course. Sometimes the site has to chip in extra money if there are not enough people that enter these WSOP qualifiers.
The freeroll is another of the WSOP qualifiers. Many sites will offer a freeroll into a satellite event but very few will offer a direct way in and those that do usually require you to meet rake requirements to play. So even the freeroll is not really free. The other drawback of the freeroll WSOP qualifiers is that so many people will enter that your chances of actually winning are pretty small.
If you are looking for the best option in terms of WSOP qualifiers you are probably best off playing in the $100-10 tourneys or taking a shot in a few smaller sub-satellites at $10-$1. The problem there is that you have to win not one, but two WSOP qualifiers.