Sony SS-d55AV. Worth it?

[blue_fAng]

There is a guy selling an amp and a pair of super old Sony SS-d55AV for 80 dollars that sounded great in his place but i dont know if it is going to be and improvement for the room where I mix (3m*4m not treated) I am on a low budget now and just a pair of decent monitors here cost around 400 usd and I live in the south of mexico in a little town, finding something used that is good and WORKS is very difficult so do you think it is worth it?? or should I save the money for good monitors?? Any experience with the ss-55's? I want to mix/master nicely btw im currently using logitech x230 pc speakers for that and my mixes and masters arent bad but i obviously want improvement. And ima noob.