Reddit has dozens of buy, sell, and trade subreddits, with communities for everything from sneakers to camera gear to mechanical keyboards. The catch is that good deals do not last. A fair listing can be posted and claimed in minutes, sometimes faster, and the person who sees it first usually wins. You cannot sit there refreshing all day, which is exactly the problem F5Bot solves.
F5Bot is a free service that watches Reddit, Hacker News, and other sites for the keywords you pick and emails you when one comes up. Point it at a marketplace subreddit and it will tell you the moment something you want gets listed.
These are the subreddits where people actually buy and sell. A few of the bigger ones:
Most of these use tags in the post title: WTS for want to sell, WTB for want to buy, and WTT for want to trade. Those tags are useful, and we will come back to them.
Say you are after a specific watch. Add it as a keyword, like "Seiko SKX," and
scope the search to the right room with only-url=/r/watchexchange/. Now when
someone lists one, you get an email with a link, and you can message the seller
before the thread fills up.
That speed is everything on a marketplace. Seeing a listing in two minutes instead of two hours is the difference between getting the item and reading "sold."
A bare keyword will catch some posts you do not want. This is where F5Bot's paid plans help. If you are a buyer, you only care about sell posts, so you can use an exclude filter to drop the WTB and WTT ones. You can require a condition or a size with an include filter. Whole-word matching keeps a model number from matching things it should not.
For the cases that are hard to pin down with exact words, F5Bot's AI-powered filtering on the top tiers can sort them for you. You describe what you are after in plain English, something like "only show me posts selling a mechanical keyboard with brown switches," and it reads each listing and keeps the ones that match.
It works in the other direction too. If you have inventory to move, watch the WTB posts for what you sell. When someone posts that they are looking for the thing you have, you can reach out while they are still looking.
This is the one use case where F5Bot's free plan delay really bites. On a fast marketplace, an alert that arrives late is an alert you cannot act on. If you are hunting deals seriously, this is the reason to upgrade. The paid plans deliver in a timely manner, which is what lets you actually be first. And whatever plan you are on, trade safely: use each subreddit's confirmed-trade and reputation systems, and be careful with anyone who wants to take the deal off-platform.
The free plan will let you watch a keyword or two to get a feel for it, with the usual limits: the delay covered above, no monitoring of the most common keywords, and a daily cap on matches per keyword. The paid plans deliver in a timely manner, raise the caps, open up common keywords, and add the include, exclude, and AI-powered filters. Compare them on the pricing page.
Pick one item you are hunting and one subreddit, make a free account, and add the
keyword with an only-url= for that community. If you are new to how the keywords
and filters work, the Reddit keyword alerts
guide covers the basics.