Find multiplayer laser tag sets and accessories at Amazon.com. Most of the products featured are for one to three players, and there are a few four player sets available, as of August 2015. Look into eBay and Craigslist for listings of new and used laser tag sets, as well.
Amazon.com is probably the best online store to find new laser tag sets for personal use. There are many other laser tag retailers, but they focus on selling equipment to laser tag facilities. EBay lists some reputable sellers offering laser tag equipment, and visitors may be able to find new and used products at good prices.
Craigslist can connect customers with local sellers and better deals on used equipment, but there isn't any guarantee of the seller's reputation. Hasbro's online store does not sell laser tag sets but allows visitors to find a store that carries the desired product. Alternatively, Lasertagparts.com has an online store that sells all the parts needed to make a own laser tag system, including starter bundles. This can be an interesting option for laser tag and DIY enthusiasts. Lasertagparts.com does not currently offer any manual or additional information on building a personal laser tag system, as of 2015.