Tab S 10.5 shouldnt exceed the RRP stated by aamsung. As far as i know, samsung is selling at 900+, definitely lower than 1000.
The difference is the origin of the product. Certain dealers get the product from distributors while some got theirs from other sources. Also, it depends on where you buy it. Large electronic stores like courts will sell at RRP while smaller dealers like Kasia Mobile will sell slightly lower with warranty..