"u'lkachtem lachem" according to the Yerushalmi

The Yerushalmi (Orlah 2) discusses whether an esrog tree which is grown l'shem mitzvah is included in the issur of orlah or not. Asks the gemara, just like an esrog of ma'aser sheni is excluded by the pasuk of u'lkachtem lachem from being used on sukkot, so too esrog shel mitzvah should be excluded from the chiyuv orlah from the pasuk areilim y'heyu lachem! Answers the gemara: the pasuk of u'lkachtem teaches that a kinyan damim is required on an esrog - it must be purchased - and ma'aser sheni is not something that is bought and sold, but the pasuk of areilim y'heyu lachem applies m'meila to any fruit. The implication of the sugya is that not only must a lulav and esrog be owned because of the word "lachem", yours, but an act of kinyan to acquire the lulav and esrog must be performed to fulfill "u'lkachtem". The Gilyon points to the R' Avigdor Kohein we saw yesterday as a source for such a reading. I do not see how you can glean that from the snippet cited by the Ketzos, and have not gotten a Shu"t haRosh to see it inside to confirm. Be that as it may, the idea is striking - can it really be that if you own your esrog but have not purchased it, e.g. it was given to you as a gift or you grew it in your backyward, that you would not fulfill the mitzvah because you failed to fulfill u'lkachtem? And if the pasuk simply means that where the lulav is not yours a full kinyan is required to acquire it (as opposed to growing your own where it is yours to begin with), why do we need u'lkachtem when we have the word lachem? Last night I found that the Dvar Avraham (II:12) addresses this issue and writes that the Yerushalmi cannot mean an esrog must literally be purchased. Rather, what it means is that the cheftza has a monetary value as something you would purchase - compare Sukkah 35 in the Bavli.