You have 3 players to upgrade but with only ten trades left I'd suggest leaving Maguire on the field until late.
That leaves you with Martin & Mayne to be upgraded.
Personally I'd suggest waiting two weeks for Fyfe to peak and downgrade him to Gourdis of Richmond or any other forward rookie you like, wouldn't stress about letting O'Keefe go past you.
That should leave you with a bit less than $200k cash to upgrade Martin with.
So...
8 trades left
Remaining cash not much
Defenders: Goddard, Hodge, Shaw, Gilbee, Enright, Maguire, Waters
(Webberley, Trengove)
Midfielders: Ablett, Bartel, Boyd, Cooney, Barlow, Premium
(Cunnington, McNeil)
Rucks: Sandilands, Hille
(Warnock, Lobbe)
Forwards: Giansiracusa, Brown, O'Keefe, Pavlich, Franklin, Pod, Mayne
(Gumbleton, Gourdis)
From their I'd hold my trades until the finals with the intention of downgrading a Webberley/Trengove/Gumbleton and upgrading a Mayne or a Maguire.
Just my thoughts.
I agree i will now be looking at upgrading Maguire ahead of Shaw last out of the 3 players i need to upgrade.
After reading everyone's thoughts i think i may look to upgrade mayne first by downgrading gumbleton, fyfe is looking good at the moment as keeping on the bench for most of the season.
Upgrading Martin will be next. I'm tempted to trade now instead of waiting a couple weeks due to tough leagues coming up.
Thanks Cynic for the feedback.