And although future appearances and promotion to the Premiership could see the final fee rise to £750,000 the 19-year-old's move to the Walkers Stadium is already looking like one of City's best ever buys.
Fryatt's 55th minute winner was one of the few bright sparks in an otherwise drab game.
Andy Welsh whipped in a cross from the left to the far post where Fryatt had drifted away from his marker to allow himself room to squeeze home a downward header between the keeper and the upright.
No wonder Fryatt was given a standing ovation when he was subbed ten minutes from time - manager Rob Kelly afterwards revealing Fryatt had been taken off as a precaution after he had turned an ankle.
The early exchanges had been scrappy, hallmarked by wayward passing and an inability by both sides to retain possession.
City produced just one moment of quality in the first half when on 15 minutes Iain Hume cleverly released Stephen Hughes whose ball across goal only just evaded Fryatt.
Plymouth had to wait until midway through the first half for their first and only threat on goal before the break, when former Fox Lilian Nalis touched a free-kick to Tony Capaldi whose 25-yard drive was easily dealt with by Paul Henderson.
The same keeper had to be alert within a minute of the restart when he got his body fully behind a powerful strike from David Norris.
Gareth Williams' long-range shot was then deflected for a corner which came to nothing before Hughes sliced a shot high and wide.
The game finally burst into life on 56 minutes when Fryatt struck, but shortly after City almost gave away an equaliser when Richard Stearman's poor back header fell short of his keeper and only a last-ditch clearance from Nils-Eric Johansson perevented Vincent Pericard from nipping in to score.
Thereafter Plymouth continued to push and probe but to little affect with City content to rely on the rapid counter-attack.
And Hume twice went close as the game entered its final stages, first clipping a shot just over following a jinking run from halfway and then bringing out the best from Romain Larrieu with a stinging 25-yard drive.