Where is the significant point of diminishing returns on hi-end turntable?


For those that don’t know me I am newish to this game. Yes, I believe this chase for perfection in sound reproduction is a game. There are endless variables affecting the sound of every system and 100x that in opinions on each of these variables. I love cool $hit as much as the next guy but I am looking for an analog rig and I keep getting drawn into the seemingly endless "what about this option that costs tons more?". I started with a $6 to $10K budget and now I am considering a $25K setup (Table, cart and phono stage) after talking to a local retailer. I will be blunt, I want to be that guy in the Memorex ad from the 80’s that is getting blown away by his system (my impression is he is overwhelmed by the amazing sound coming from that speaker not the volume). Now that I have acquired some pretty descent stuff I am spending 15 plus hours each week listening and really enjoying this hobby. I don’t want to have any regrets and just be marginally satisfied with my setup but where do I draw the line? Back to my initial question; what is a reasonable amount to spend on an analog setup to achieve the best bang for the buck? I may be somewhat unique in that I don’t want to constantly be upgrading my equipment, I just want to buy great products the first time that are very satisfying and spend hours listening to great music. I don’t want to be the guy always chasing the next great thing.
128x128mmporsche
How about a relative way of looking at it such as ’equal to the amount spent on speakers’ or ’1.5 x amp + pre’?

I just did a quick calculation: I spent 66% more on my analog front end than on my speakers. In fact the  analog front end was almost equal to 

A methodology such as this very loosely correlated what the system will be able to deliver at the ear.
Lewm- how wonderful that you had stewardship of that car. Thanks for the reply. I'm not a "Porsche guy" (though I've owned a few of them and have enormous respect for the marque). The question--not to derail this thread- is whether you'd be willing to put such a valuable car in traffic today. I admire the people who do, but it takes a certain mindset. Good for you! 
whart,whenever I drive a 356 or similar car on the roads today, I always drive in one mode only----Defensive!! To say it takes a certain mindset is so very true...........but its better than having the vehicle rot away as a trailer queen, lol.
Davey- yes, and the same thing comes up (at a slightly different cost/risk) with certain valuable old pressings. I choose to play them rather than keep them on a shelf for posterity. As far as public roads go, it's the wild west out there! Drive safe. 
This thread is inspiring me to set up my old Rega Planar II in the back seat of my Porsche 911. Maybe a McIntosh car amp in between, and some of those Gallo speakers over the dash? I’m guessing the point of diminishing returns would come mighty quick (at least that’s one clear answer for the OP).