I don't think there's really a one-size-fits-all essential toy list for camming -- it really depends on what kind of shows you plan on doing. My most used toys as someone who primarily does femdom & clit-based orgasm play:
- Strap-on + Various Attachments. I actually own a really high-quality, custom made leather harness that I love because I use strap-on toys in my personal life too, but honestly my cheap-o nylon piece has been just as popular, so I'd stick with something like that if it's just for roleplay.
- Dildos for JOI, SPH, trampling, humiliation, etc. I don't do penetration with these toys, so I don't have to worry about always buying body safe materials. I just buy whatever's neat/cheap at the time.
- Various BDSM toys. I own everything from a piggy tail buttplug, to paddles, to violetwands. You certainly don't need to own all of these things, but there are lots of fairly inexpensive kink toys out there if you want to add variety to your shows or cater to specific fetishes.
- Clit-play toys. For me that currently means Hitachi, Shibari Halo Wand, We-Vibe Tango, Satisfyer/Womanizer and a handful of other vibes that I keep in rotation. I also own a Sybian, which has been very popular for me, but definitely isn't a starter toy. If I had to pick one or two things, I'd say a decent wand (Shibari Halo, Hitachi Rechargeable, Doxy, etc) and some kind of bullet (We-Vibe Tango, Lovense Ambi, Jimmyjane Form 2, etc) would do.
- Misc: Oil, lotion, stockings.
I don't do penetration play on cam, but if I did, I would definitely invest in high-quality, body-safe rabbit-style vibe (the We-Vibe Nova looks cool!), a silicone suction cup dildo, and some nice, smooth glass toys. I'd also throw a steel or glass buttplug into the mix for good meassure. A realistic dildo for doing bj shows, like EmiliaSong mentioned, is also a good plan.
If I did more on the bottoming side of things, my basics would probably be: simple leather (or "leather") cuffs, a paddle, a ballgag, nipple clamps, collar&leash, washable markers.
Interactive toys are neat but definitely not a requirement. I've been camming for.. 4?.. years and have only just pre-ordered some myself.
I'm super rambly today, but hopefully some of that helped anyway.