A few thoughts to start with.
Hi Anton, and Welcome to the Great American Roadtrip Forum.
There is one omission in your map. If you start in SF and head to LA via the coast road, then to GC, LV and DV, you would head straight up to Tioga Pass CA120, and enter Yosemite from the east side, then head back to SF to drop off the car. You won't need a car in SF so don't pick it up till you are ready to head for LA. Be aware that the coast road is a two day drive.
Flights - look for the cheapest flights on the internet. Most of the flights are listed on the consolidators pages.
Accommodation - the cheapest would be camping. You could pick up a cheap tent and sleeping bags and mats on your arrival in SF. Maybe even pick up some cooking/eating items in a charity shop.
Rental car - Because you are both under 25, and probably both want to drive, you will be subject to the young drivers surcharge, which could be as much as $25 per driver per day. Many European visitors have managed to get these extra fees reduced or even waived by going through a European consolidator. So do your homework there, and see what you can come up with.
The trip you are planning is probably the most discussed trip on these forums, so spend some time reading around the forums. Do you have some good maps of the west coast? If not, I suggest you go out and get some, so you will be able to see all the details which you cannot see on a small screen. And be aware that the travel times shown on computer programs are pure fantasy. You need to add at least 20%, or divide the miles to be driven by 55, to get a more realistic time of how long a journey will take.
If you are not able to get good maps locally, I recommend that you purchase a Rand McNally road atlas from the RTA store via the link at the bottom of this page. If you order it now you will have it in a couple of weeks. Good detailed maps are invaluable during the planning of a trip, and essential when on the road.
Enjoy the planning.
Lifey
Planning is part of the fun.
Quote:
There are so many airlines and travel agencies, I can't seem to find solid travel plans or deals fitting our plan nor budget.
You will do much better by doing the planning yourselves and it's a fun part of the experience. 'Travel agents' are just doing a job and do not have the same enthusiasm for your trip as you will that will turn it into a unique and memorable trip. In fact we often have had new members join and share what their Travel agent has planned out for them only to find out there were big errors in the plans. Plane tickets, hotel rooms and car rentals can be found on line, just keep checking back as deals are constantly changing and the more you look, the better equipped you are to spot a good deal. Even trying different days of the week can throw up differences.