Earlier today Bluegrass Cellular announced that it will offer Apple’s iPhone 4S to its customers starting on May 18. Now regional carriers Pioneer Cellular of Oklahoma, Golden State Cellular of California, and Nex-Tech Wireless of Kansas have announced they will also offer the smartphone on the same date. Pricing starts at $149 for the 16GB model, $249 for the 32GB model, and $349 for the top of the line 64GB variant. Pioneer Cellular also said that it is, starting today, offering the iPhone 4 to its customers for $50.