Depends on how you go about it. Most of the shop will advice you to go for new bike instead of upgrading bits by bits. I would like to share my experience with you all here.
I started with Proton T-bolt in 2008 where I got it for RM950. Full sus, carbon frame with Deore and LX group set. Tektro mechanical disc brake etc..
4 years later (2011) I decided to upgrade to hardtail frame. I went to KSH SS2 (Now Pedalspot) ask them for some good frame that is rugged and can support my weight (105kg). I don't really care if it's off season frame of new frame. Finally this Wong introduced my 2010 Merida Matts TFS 500 XC 6061 frame for RM1.3K. Immediately I knew I am attracted to that frame. I pay RM1.3K for the frame upgrade with SRAM X7 FD (T-bolt FD unable to fit into hard tail) and Jagwire Shifters cable.
Everything from T-bolt got transfered into the new frame include the seatpost as well. Later I started to ride with new frame. The feeling is totally different from riding full sus. I did a lot of upgrade in 2011 when I ride a lot (Almost every weekend!). 10 months later, I upgraded my fork to Rockshox SID 2011. I had to fork out RM1580 for the upgrade. Nevertheless, the ride is different.
I met my friend who bring me into Kiara for the first time. There onwards, I started to ride in Kiara, no other place else. Then, things changed, I know I need a bike that can handle trail in kiara while still maintain it for XC when needed. I decided to upgrade my cockpit to fit well with my body. I changed my stem to 90mm Thomsom with 620mm TITEC Carbon fibre flat bar. I forked out around RM600 bucks for that upgrade. Another week, I changed the grip to Ergon GX1 which cost me 35SGD.
The more I ride the more I enjoy it. I tried to upgrade my skill as well. Then I realize there's limitation in my cable disc brake. 5 months later, I upgraded my brake to Avid XO Silver 2011 brake. I realized that I get more daring when I knew I am in control with better brake. I try to go faster and corner more.
There's once, I had overlook the importance of wheelset and tire. I endo when I was riding 2K and crashed my biken twice on different occasion. Did some post mortem on the incident and realized that my tire had expired since the day I bought my T-bolt and there's some dent on my rim as well. I decided to upgrade my wheelset and tire. Hence I spent 680SGD on ZTR Arch EX + Hope Pro 2 Evo and 100SGD on Kenda Nevegal 2.35 + Kenda Nexcavator 2.1 setup.
Till today, when I look back the amount I spend on my bike. People would say you're crazy. Not to mention, I spend on Avid Pro Bleed kit, MINOURA wheel truing kit, bike repair tools, brake fluid, grease, fork oil etc. Do the math, for all the upgrade I did definitely cost more than RM6K easily.
My friend keep on asking me, how often do you use it? I would just smile and tell them, I will fully utilize the stuff I buy. Don't misunderstood that I am trying to show off what I had upgraded. Different people have different opinion. Most of my friend will just advice me go and get a new bike instead of paying so much for all the upgrade.
As you can see here, till today I still running my old T-bolt seat post, group set. After all these years, I still didn't' change my chain. I got a bike computer on my bike and it show's that my new frame already clock more than 700 hours of ride. Not to mention the group set is definitely more than that.
IMHO, biking is not just about upgrading the bike, but also upgrading your biking skill and the most important - enjoying it!
That's all forks! Just my 2 cent sharing!

Wow... You actually pay for a Merida frame