Plato, Phdr. 228a

Πῶς λέγεις, ὦ βέλτιστε Σώκρατες; οἴει με, ἃ Λυσίας ἐν πολλῷ χρόνῳ κατὰ σχολὴν συνέθηκε, δεινότατος ὢν τῶν νῦν γράφειν, ταῦτα ἰδιώτην ὄντα ἀπομνημονεύσειν ἀξίως ἐκείνου; πολλοῦ γε δέω· καίτοι ἐβουλόμην γ’ ἂν μᾶλλον ἤ μοι πολὺ χρυσίον γενέσθαι.
Is “ἐβουλόμην ἂν” here to be taken as counterfactual, with καίτοι meaning, accordingly, “even if…”; i.e., implying that he actually does not wish it so much as to prefer it to any amount of gold?

He’s saying it’s unrealistic to expect him, a rank amateur, to recount from memory Lysias’ laboriously painstaking composition in a manner worthy of such an expert speechwriter; he’s far from capable of it; and yet (καιτοι) he very much wishes he could. (More precisely, he’d want to, more than getting a truckload of gold.) καίτοι could never mean “even if.”
Incidentally, I’d prefer εμὲ (or ’μέ) to the enclitic after οἴει.

Thanks a lot, Michael. Any idea, then, why the potential here is indicative, not optative?

I think, I got. He would want to become capable if this were achievable. The assumption seems to be that one cannot wish the impossible; hence the counterfactual element.

Impf. indic rather than (pres.) opt: he would be wanting (now as they speak). Pres. unfulfilled—counterfactual, as you put it. There’s no protasis.
It’s more or less equivalent to Eng. “I’d like to, more than anything.” (but I can’t. Τhat’s already been said: πολλου γε δεω)

English “I’d want to…” in its current usage seems to be just a polite form of “I want”; yet the literal meaning seems to be that I would want it if it were possible to satisfy such wish; but since it actually is not, I do not actually even want the thing in question.

“but I can’t. Τhat’s already been said: πολλου γε δεω” – This is why a concessive meaning seems to suggest itself for καίτοι: "I cannot, although I’d want to… " But LSJ say καίτοι doesn’t have such meaning with finite verbs…

It’s a perfectly ordinary use of καιτοι, “And yet,” introducing an independent clause (so not “although”).
The sequence is “… No way can I do that (πολλου γε δεω)—and yet I’d dearly love to.”

It’s a perfectly ordinary use of καιτοι, “And yet,” introducing an independent clause (so not “although”). The sequence of thought is “… No way can I do that (πολλου γε δεω)—and yet I’d dearly love to.” See my first post above.

Thanks, this makes sense. Alexander Nehamas translates: “Far from it—though actually I would rather be able to do that than come into a large fortune!”

And two Russian translations render καίτοι here as “even if”; hence my initial question.

You’d do better not to rely on translations, which don’t necessarily follow the structure of the Greek. First try to understand the Greek (and the Greek syntax) itself. Then you’ll be less likely to tie yourself up in knots as you did here.

Here καιτοι could indeed be rendered “though …” or even “even if” as an afterthought (hence my dash before “and yet”), despite the fact that it changes the syntax and doesn’t introduce a subordinate clause.
“Mind you, …” would convey the sense well.

Good point. Actually, I never rely on translations but am only using them to double check whether I got the Greek right. In this case, I had doubts, as Russian translations contradicted my initial understanding.