I have done something like this to my ej9, suspension wise so I will let you know about the prices.
-26mm front swaybay (the same as ek4 one) bolt on if your ej9 has a front one 50e most
-ASR rear swaybar kit with 24mm swaybar (stronger and bigger rear swaybar, stronger end links) something around 300e but you can get cheaper ones if they are used
-for 150e you can get the whole package from energy suspension, uprated strong bushings better than oem and will last for life. You change almost any bushing existing on the car, it feels great, rigidity increase, responsive chassis etc
-reinforcement bars. the ek4 stock one costs 20euros to get it from honda dealers, there are thousands of them used on here and everywhere, the same with bumper bars.
-600-700pounds for a new decent coilover kit
-then if you want an alignement refinement you can get some caster or camber kit which doesn't cost a fortune too.
I think that with 1300-1500e most you can have a really sport tuned civic which does whatever you tell it to on the road. Agile, responsive, slightly oversteering etc..
The lsd is related to the engine output mainly. An ej9 with 120-130hp doesn't really need it. And bear in mind that an ej9 3door weighs from 950 to 1040 kg which is good for handling.