eBay's search function is really very powerful, with many options and boolean logic capabilities. It would behoove you to learn it well.
Coupla quick hints to get ya started:
Logical AND: iThis is the default. If you search for:
pa knives
...you'll get every entry that includes both "pa" AND "knives", regardless of order.
Exact Phrase: this comes in real handy, too. By enclosing you search in quotes:
"pa knives"
... you only get entries that includes that exact phrase. It will not match "knives pa", or "pa brand knives", for instance. Still, it can help limit your results to what you really need.
Logical OR: This lets you search for multiple words or terms:
(pa,penn,pennsylvania)
...will give you all entries that include the words "pa" OR "penn" OR "pennsylvania". You can combine both AND and OR:
(pa,penn,pennsylvania) (knife,knives)
...will give you all entries that include the words "pa" OR "penn" OR "pennsylvania", AND the words "knife" OR "knives".
Negation: you can use this to EXCLUDE words or phrases:
-(case,queen,schatt)
...tells eBay to NOT show you entries that include "case" OR "queen" OR "schatt". This can help you weed out stuff you know you *don't* want.
So, an example... let's say you're interested in oddball-brand knives made in Pennsylvania, specifically split-backspring whittlers. You might try searching for this:
(pa,penn,pennsylvania) ("split backspring","split-backspring") whittler -(case,queen,schatt)
To cast your net wider, be sure to check the box that says "search title AND description".
Note that I entered the phrase "split backspring" two ways; eBay is sensitive to punctuation, which can complicate matters. You've probably seen enough auctions to have an idea of the terminology that sellers use; keep that in mind when you build your searches!
Also, you might want to limit your search to certain sub-categories, although some of the best bargains I've found were listed in the wrong category!
Oh, and one last thing: once you've crafted a search that gets you waht you want, save it by clicking the link near the top that says "Add to Favorites". That way you don't need to remember the formula later.
Have fun!!