Our all budget is $6000 for the equipment and the company is going make a microwave doppler motion detector.
If it's being bought for a specific design task (radar) then I would think that the designer of the radar would want to dictate the specs for the analyser.
For example: Does your radar require low system phase noise? For some flavours of Doppler radar, phase noise can be key to the system performance. Neither of those analysers will be of much use for measuring (low) phase noise. But you can always measure system phase noise with something else and just use the analyser for basic signal monitoring etc.
The problem with buying an older/cheaper Agilent or HP analyser is that you will lose much of the modern connectivity and also the data capture/transfer will be more limited. But the RF performance will be a lot better.
So you need to decide which is most relevant to your needs.
GSP-930 is equipped with various interfaces, including LXI, USB, RS-232 and GPIB (optional). The IVI driver is available for the remote control software development by means of LabVIEW or LabWindows/CVI. A Micro SD slot and a USB Host interface enable the memory size expansion for mass data storage. An IF output (886MHz) is provided as the intermediate frequency signal of RF inputfor users to develop their own applications. Carrying abundant communication interfaces, user-friendly operation, large screen display, light weight, compact size, and battery power operation(1), GSP-930 is developed upon a high-tech platform to provide ultimate customer benefits.
That looks to be a very modern/versatile development platform so assuming that all the above interfaces actually work and aren't buggy then this probably puts it ahead of the Rigol in this respect. But you need to find out if your designer cares about the high phase noise and the limited RF linearity of either analyser