Observed Trials Gear
Finding riding gear for observed trials riding is not as easy as finding motocross or trail riding gear. While some of the dirt bike gear is interchangeable and will definitely work for beginners, trials riding is a specialized arm of off-road riding and requires some trials-specific gear. All riders should wear a helmet but after that, each rider will need to decide for themselves how much gear to buy. Beginners probably aren't going to need a pair of $350 trials boots, but probably will need a $50 set of elbow pads. The reverse is true of experienced riders.
Trials helmets: Trials helmets are open-faced helmets as opposed to the full-faced motocross and off-road helmets. Trials riding is about precision, not speed, and riders need an open field of vision in order to hop from one obstacle to another, but still need protection from falls. Some beginning trials riders use either a street bike or motocross helmet and a few even use a bicycle helmet which is better than nothing, but not recommended. A few brand names in trials helmets are Wulfsport, Spada, and Airoh. Amazon sells the Spada Edge Explorer trials helmet, but only occasionally stocks the Airoh TRR and Airoh Evergreen helmets. If they're not in stock (you'll get a 404 page) the only other Amazon option for the helmet would be Amazon.co.uk. Check the shipping costs if shopping on Amazon UK as shipping isn't always free, and keep exchange rates in mind as well.
Trials boots:Trials boots look similar to motocross boots, but are softer, 'grippier', and more flexible than motocross boots. If you decide to stick with riding trials, a good pair of boots will make all the difference because unlike motocross or trail riding, you're standing on the footpegs the entire time you're on a trials bike. The softer sole also allows you to 'feel' the bike more. Boots seem to be the most widely available component of trials apparel, and Amazon sells both the Gaerne Balance boot as well as the Alpinestars No Stop boot. A more in-depth look at a few more trials boots can be found on the trials boots page.
Trials apparel: If you're a trail or motocross rider looking to try trials bikes for cross training, you should be able to use the jersey and pants you already have and buy some trials-specific apparel if you decide to stick with it. For those with no gear (trail, MX, or otherwise), you'll need to decide whether to invest in some trials gear. If you've already purchased a bike it's a no-brainer but if you're still deciding, the apparel isn't imperative. The pants pictured are from Hebo and even though they're not US-based, their 2017 PDF catalog will give you an idea of what trials gear is available on the market so you can do more research. Based in England, Trials UK is another good site to look through for more info on gear and apparel.
Trials training DVDs: Ryan Young released a couple of trials training videos a few years back that offer some good advice for getting started with trials bikes. His Basic Skills and Cross Training DVD, and his Advanced Training DVD are usually available on Amazon, or check Ebay, or try Ryan's website to see if you can get a better price.
Finding more trials info: Your best bet for finding more info about the best trials gear (and where to buy it) is to join a club, spend a day at an event, or email the contact person on a website that you found. Both the NATC (North American Trials Council) and the Trials Training Center websites might be good places to start. Trials bikes are great fun, but they're still not quite as mainstream here in America as they are in Europe, and trials gear and training resources will be tougher to find.