Of course it is not a JSTARS - The fundamental difference being that it is a "collector" while the JSTARS is the "Collector" and "Analyzer" of the data. The JSTARS-Recap, even with the USAF is only at an RFP submission stage and the two radars are at a prototype stage. The capability Raytheon has presented to multiple customers is based on its work on the UK Sentinels and is just about as advanced a capability a US OEM can market without requiring hundreds of millions to billions of $ to develop something from scratch. JSTARS-Recap has to go through source selection, technology development/EMD, Developmental testing, Operational testing and then IOC/FOC. That is not compatible with the requirements the MOD/IAF handed over to bidders years ago for this program.
Sentinels that UK can't decide whether to keep or ditch.
What does UK MOD budgets and dollars have to do with the IAF and its acquisition plans? The UK can at this very stage also not afford MPA (until early 2020s). Does this mean the IN should not have acquired P-8s? The UK may well decide to mate the AAS on some of its P-8s and re-gain the ASTOR capability if they end up retiring their fleet. A changing budgetary environment is getting them to think about priorities, and with their effort in Afghanistan winding down this is a legitimate area for them to consider downsizing if they have to choose between something they need less in the short-medium term vs something that they may need to modernize quickly.
Unlike the UK, India does not have the liberty to pick and choose which ground campaigns to get involved in and which to pass over since the main strategic threats share a very larger border and aren't separated like is the case with the UK.
$1billion sounds too low for JSTARS kind of aircraft
For ISTAR aircraft based on a business jet it sounds about right. A lot has happened on the electronics side of the industry since the Sentinels were delivered to the UK so expect a lower cost overall for the Dual Mode AESA radar, and other high tech. electronic components.