I need advise

[JAZZCNC]

I am so much scared of DIY build because I don't no much about Cnc routers and I will not no were to start from it will be even worse when it comes to electrics and programming

Well it's not difficult has you probably imagine.!
The scary stuff like electrics is actually very easy these days. Like wise the sourcing of components is easier than ever and can be quite cheap if sourced from known sellers which you'll easily find on the forum.
The design of machine and components required will depend on the main use. If these are known and clear goals defined then how the rest of the build goes depends greatly on your skills and equipment.
To be honest if you have the skills and equipment you'll still only build the machine for about the same money 2.5-3K. . . BUT. . It will or should be a far better machine custom to your needs using modern digital drives and higher quality components.

If you need to be up and running quickly then Regards this machine if you can get it for 2.5-3K and all the mechanical items like ballscrews, linear rails are ok and not worn out then yes buy it. . . BUT IMPORTANT. . you need to see it first and if possible take someone who knows CNC and can check the mechanical components.

Edit: Oh and the programming is essentially the same on any machine and area where lots of people struggle at first.
I'll warn you know Your needs for 3D models and signs is not basic stuff.!! To achieve good results takes time and fair knowledge of the programs used to create both models and the tool-paths required for cutting.
CAM software with good 3D tool-path strategies isn't cheap and can easily cost half the price of the machine or more and this machine I'm sure won't be coming with any CAM or CAD software.