A $300 Saiga is not what you'd call an "AK47" unless it has been converted by someone like Arsenal, inc or RedJacket firearms.
Not even then! The Saiga uses a smaller AK-74 bolt head and carrier...it will never be even a semi version of the 47. Basically, they reamed out 5.45X39 bolt. Many also have a nice litte step in the chaimber, none have a bullet guide from the factory.
Gen. M. Kalashnikov himself is so un-involved in production these days, he was not even told the russian army cancled the orders for the 74's:
"News of the army's decision is reportedly being kept from the rifle's designer, Mikhail Kalashnikov, now 91.
"We do not want to take it upon ourselves to tell him," an unnamed member of his family told Russia's Izvestia newspaper.
http://www.bbc.co.uk/news/world-europe-15076757
The flip side is the Siagas have a good reputation for being accurate, but if your the type who like to fill the rifle full of sand ( which I do not), shake it off and fire...good luck, the accuracy is due to tighter tolerances in the '74 version.
WASR's ( even used) go for more money than the (unconverted Saigas), that is why they MIGHT let you trade.
I would save up for the saiga if you want one so bad, you could always trade it later.