I saw a swallow 90 size ARTF second hand with the servos and supertiger 90 for 390 AUS in it but the shop owner says the engine is tired. Is the plane worth buying?

I had one.

They're not a bad machine once you sort out all the bugs,

THe St G90 can be made to go pretty hard.

Where is it? you mention AUD, so I'm assuming you mean australian dollars.

They are not a bad plane..narrow and fast!!
landing gear is suspect...anything more that a fair landing will rool it off the plane.

Don't know about the engine, but the airframe when properly set up behaves very much like a pattern ship, smooth and well behaved. I had no problem with landing gear, but I did crack the fuselage behind the wing trailing edge. Newer product has that area reinforced with fiberglass. Original trim covering is useless, peels off quick. I recovered mine before I ever flew it. I used a YS 110, which suited it perfectly. I crashed mine after a moment's lapse of concentration, but got another. This model is definitely competitive in the lower classes.

well is in aus and ye is aus dollars and so it shud suit me seeing i fly sportsmans routine