So, if you saw my last post, you can see one of the many reasons why I'm a fan of trekking poles. I also like my ankles to stay unbroken and functional. Those of you who know me offline know that this is a battle I do not always win. Those of you just tuning in, take my word for it, it's hard being my ankles. Certain Tent Designs, like the A-shape tent I link in my Cheap Gear List (which I intend to update for next season!) can actually replace it's poles with trekking poles. So, I really am a believer in trekking poles, and I don't regret a single cent I spent on my REI Traverse Poles, but at the same time I can see how someone might balk at $90 for a pair.
I've been thinking of pestering some friends with Costco memberships to sneak me into their walled garden, to get a look at the fabled $30 trekking poles reputedly sold there. But, I did a little research, and you can get them just as cheap on Amazon. Woah, woah, slow your roll, the $30 pair is basically a no-go. $30 gets you foam rubber grips, and twist locks. The handgrips are fine if you're snowshoeing or something where you're wearing gloves, and I suppose they'd do in a pinch, but take my word on it, you want cork grips. Meanwhile, twist-locks are just a cardinal sin and no mitigating circumstances exist to justify them other than "they cost less." But if I'm spending good money on poles to keep me upright, they damn well better keep me upright.
So, all is not lost, but they'll cost you a little more than that initial $30 pricetag. $48 on amazon will get you a set of Cascade Mountain Tech Flip-lock Trekking Poles. They have cork grips, for which your hands will thank you. They're carbon fiber, so they're possibly even lighter than mine. You get carbide tips inside of rubber stoppers, so you can choose what's appropriate for your use-case. Flip-locks are that much less likely to betray you when you need them most, and they're half of what I paid for my entirely reasonable REI branded poles. Especially at the entry level there's no need to lay out the $160+ that some of the brands can run.
The only thing I can think of that'd be cheaper, and still worth using, is to find some used ski poles at a garage sale. But then you don't get the cork grips.
This isn't exactly an endorsement per-se, but it is a heads up on something that I've heard other people endorse. If you pick some of these up, I'd love to hear how they work out for you. I'd be glad to link to, or include your review of them here.