I totally feel your pain with the flexible leg stuff... they just dont cut it for serious long exposures. Iceland wind is no joke, it literally blows car doors off the hinges sometimes, so you definitely need something with rigid legs. Since youre trying to stay under 100 bucks, you might want to consider these aluminum options. Theyre slightly heavier than carbon fiber but way better than a flopping GorillaPod. Here are some suggestions based on what Ive dragged through the mud before:

• Sirui T-005S Traveler Ultralight Aluminum Tripod with B-00K Ball Head. This one is honestly perfect for the RX100. Its tiny when folded but has a center column hook. I would suggest hanging your camera bag from that hook to weigh it down in the wind. Just be careful not to over-tighten the ball head.
• Manfrotto Element MII Aluminum Travel Tripod. This is a bit more robust and stays within your budget. Make sure to check the leg locks regularly because salt spray and sand in Iceland can really gunk them up.
• SmallRig Selection T10 Aluminum Alloy Tripod. Its very budget friendly and surprisingly stable for the price. Just a heads up, make sure whatever you buy is tall enough so you arent crouching in the snow for hours. Also, maybe grab a cheap remote shutter so you arent touching the camera and causing shake. Feel free to ask if you need more help with the settings for the lights!

Ive spent years traveling and once had a cheap tripod literally shatter in the wind.

• Avoid plastic parts
• Keep center columns down
• Try a weighted beanbag

Wait, before you buy anything... are you planning to shoot from the ground mostly or do you really need full eye-level height? Iceland wind is no joke and will turn a tall, cheap tripod into a kite, especially with a light camera like the RX100. Honestly, ive seen gear get trashed because people went too high in a gale. In my experience, if you want to stay under $100 and actually keep that camera still, these two are way more reliable than those bendy things:

• Sirui AM-005K Aluminum Travel Tripod with B-00K Ball Head
• This is basically my go-to for small setups. It is aluminum so it has some weight which helps in the wind, and the build quality is actually legit. It feels way more expensive than it is.
• Benro Slim Aluminum Lightweight Tripod
• This one is super thin but surprisingly rigid. The twist locks are fast and dont get jammed with sand or ice as easily as some other designs. I'd personally lean toward the Sirui tho. It's survived my clumsiness for years and it's super compact. Just make sure you hang your backpack from the center hook if things get really hairy out there near the waterfalls... that extra weight is a lifesaver.