interested in hair extensions-need help!!

Just had a consultation for hair extensions. The hair is raw/virgin hair from Russia or Poland on hand made wefts. The hair is attached by a platinum or silver link to the root area of the hair. I was assured these would not harm my hair & could actually help it grow stronger. I was told they could last almost 2 years. The extensions would take about 8 hours to put in & would need to be adjusted about every 8-12 weeks. The price I was quoted for hair to my shoulder blades was $6500.00. Is this reasonable?? My hair is super fine & fragile but I like to wear it long. I don`t want to do anything that will cause a lot of damage. Any comments would really be appreciated. Thanks.