You need to search NCBI database for SSRs/ EST-SSRs in desired species. Then either you design your primer or look for previous studies with characterized SSRs of your interest. Once you have sequences of Farward/Reverese primers you can place order to commercial biotech companies for primers pair. Yeah as Poly acrylamide gel (PAGE) has higher resolution power, it will resolve your PCR product more precisely, with even few bp differences. Best of luck