I built my own lab. After tallying up the cost of the equipment, books, CBT's, and Narbik bookcamp I've got about 12k invested in my CCIE studies. Now, you can purchase a beefy computer, throw a bunch of NIC's in, and install GNS3 along with four switches and you could have functioning lab. My gripes with virtual solutions like GNS3 are a) when the lab goes to 15.x code you won't be able to use it anymore and b) you will encounter some bugs where certain features don't act like they should and you'll be left wondering if the problem is IOS or the virtualization product.
A lot of people go with rack rentals, but it all depends on what track you are pursuing. If you are going data center then you must rent because you won't be able to afford the gear. The two main drawbacks to rentals are a) that you typically have to reserve them in blocks of hours and if you don't use all of your time you end up wasting money and b) scheduling conflicts arise since there are only so many racks and so many hours in the day. With rentals you don't need to invest money in hardware and power. For what it's worth INE is really good for renting.
