Let me explain it to ya...
It boils down to desire.. If you believe you can, you will. If you believe you can not, you never will.
Everything else is just details..
Our first trip to the dunes was many years ago, and like most, we just rode down to Cantamar in the Ranchero..
No buggy, no bike, no nothing but a tent and two sleeping bags.
This entertainment continued for some time.. Begging rides with more affluent folks..
However, we were hooked instantly..
I started collecting "Stuff".
A noisy VW crash box, free.
A 40 HP engine, free and frozen.
Stock rims and beater tires.
Checking the ads every day, I found a crashed 1968 VW for sale, no trans, no engine, no wire loom no tires/rims. $25.00...
Dragging that home, and the race was on..
In those days, VW had very good prices for parts.. main and Rod bearings, and gasket kit $25.00.

(Those days are long gone)
Next month, I had a road worthy Baja bug.. Yes, I used a gig saw to remove anything that didn't look like a Baja.. No fiberglass..
I simply removed the bent metal..
That Baja ("Betsy") made many trips to Baja, Pismo, and finally, Mother Glamis.. Nirvana indeed.. Total build cost, $50.00 and a lot of sweat..
Clearly, we spent more as time wore on. But budget never left our focus..
If you believe, you can do it..