There is no guarantee for a neo to develop blue. You will run a better chance though with red neos which is why they are more money. Dont be fooled if anyone tries and sells you a 'southern' chondro such as an Aru or Merauke red neo as true southerns dont have reds, only yellows. The northerns like Biaks, Sorongs and Manoks have reds.
Also be careful about adults that are bright blue as females will go hormonal blue sometimes and keep the color for a while.
And you can expect to pay a lot more than $1500 for some of them. Generally USCBB red neos will run you at least $900.
As for some other breeders, there is Ian Bessell from S&J. There is also Justin Wilbanks who i bought Alex from but he deals pretty much in Biak and Biak crosses. There is also TK Chondros and Southern Chondros. There is also Bill Stegall and another who i cant remember atm lol.
Also if looking for a high yellow, be wary as some people will try and sell Biaks as high yellows since they usually hold their baby colors for 3-5 years. I personally havent seen many high yellows aka Kofiau Island ones for sale.
Here is a pic of Alex's dad who is an OSHY( Ophiological Services High Yellow aka Eugene Bessett). Thing is with GTPs, its all a gamble. The ugly duckling of the clutch could turn out to be the best and the best looking baby could turn out to be a blah adult.
I am actually debating on getting another GTP once Alex's AP cage gets here. Thinking of getting an Aru this round or maybe a manok red neo since i have two Biaks already.