I use just very often in speech and casual writing. I tend to edit it out of more formal writing. I am a native American English speaker from Tampa and Boston.
To me, it can have both meanings, and I don't think that I have a preference. Your examples are all ambiguous to me. I think that the meaning is often clear from context (don't underestimate the power of context!), as in:
1) I'll be there soon. I just woke up. (recently)
2) I didn't call her. I just sent her an email. (merely)
3) I tried, but I just don't understand. (simply)
I don't see how changing tenses or aspects can help you, except that the future and simple present (always?) rule out the recently interpretation. But all of the following are equally ambiguous to me (sans disambiguating context).
4) I [just ate/am just eating/was just eating/have just eaten/etc.] an apple.
When I want to be crystal clear, I just replace just with merely, only, simply, or suchlike. I think that I less often change just to recently. I think I more often say just now to indicate that I mean recently.
Best Answer
First of all, dictionaries list both spellings, and pricy is generally listed as a variant spelling of pricey, not the other way round, at least in the dictionaries I have checked (Merriam-Webster, Wiktionary, New Oxford American Dictionary, American Heritage Dictionary, Cambridge Dictionaries Online).
Secondly, the usage stats from the Corpus of Contemporary American English (COCA) and the British National Corpus (BNC) look as follows:
As you can see, this is not an American vs. British English thing. Pricey is clearly more popular on both sides of the pond.
Furthermore, the Corpus of Historical American English (COHA) paints the following picture:
(X axis: year, Y axis: absolute number of hits.)
So, this suggests three things, at least for American English:
So the bottom line is: both spellings are correct, but if you want to be on the safe side, pricey is the way to go.