hi!
thanks for reply retrolefty. i think i will have to do some reading on shift registers, but as i understand at the moment it's a way to read multiple sensors into single input?
i discovered "reflectance sensor that carries a single infrared LED and phototransistor pair in an inexpensive, tiny 0.5" x 0.3" module" at polulu [Pololu - QTR-1RC Reflectance Sensor]. maybe this could work out, althouth 361 of them is quite a lot. it kills about half of my budget.