Buy or Rent Circus Equipment
Of course you can buy some juggling beanbags and an instructional DVD without too much problem.
Before investing in professional quality equipment, however, you may want to go somewhere where you can look at and handle the available equipment (even if you do eventually buy it online). You may visit specialist shops, attend local workshops, or go to one of the conventions (juggling, unicycling, etc) where you will find trading stalls.
Suppliers
Community Workshops
Events
If you intend to learn one of the potentially dangerous skills (stilts, unicycle, rolla-bolla, etc) you need to take at least as much care as you would learning (say) skateboarding. You might benefit from learning the skill first (at least at a basic level) before investing in equipment, so that you choose something that really suits your needs.
Rigging for aerial work is such a specialised area that it should not be attempted without training. The people who can advise you on the skills needed can also tell you about finding equipment or having it made.
