Hard to find with Spyderco because they are in demand.
If budget is an issue you could always look for a used Byrd (Spyderco's budget brand). A Tenacious is a good knife at a real good price, maybe doesn't get as much good publicity since it is Chinese made. Personally I think the Delica or Endura are what you need, or maybe the Stretch. I don't think there is any need for you to spend more than that, although the mentioned Manix 2 is a good deal for what you get. You will have a much easier time sharpening the standard Delica, Endura or Tenacious.
I think if you want clean cuts of stems you would want a plain edge or at least a combo edge. The serrations would come in handy cutting other things like zip ties, heavy string or thicker stalks.
You can check the for sale areas here for bargains, or look for online auctions. There is a "wanted" area here where you can post requests but it seems to be mostly dead. You never know, someone might see your request there.
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You bought a PM2? The PM2 is one of the best knives Spyderco makes for everyday use. I didn't recommend it because it is normally more expensive than other knives that would serve you well, but it is hard to beat unless you needed something larger.