I'm also considering using toilet paper rolls. Cut them in half and tape one end and fill with some soil add seeds and at the time of planting just put the whole thing in the garden after removing the tape of course.

I am all for exploring new ways and methods of seed starting. If one system works better than another for you, then use it, of course. Having said that, let me respond to your post with my experiences in the toilet paper roll and egg shell methods you mentioned - with the understanding that it was my personal experience and others may have better results.
Starting with the toilet paper roll method. One year I saved up a lot of toilet paper rolls and made lots of pots for seed starting. The seeds started and things looked pretty good at the start. Maybe if I would have transplanted them in the first week or so after sprouting, that paper roll method would have worked for me.
But I start my plants inside about 6-8 weeks before transplanting in my gardens at the end of May where I live. Somewhere around week 3 or 4 of starting the seeds in the toilet paper rolls, the paper rolls developed lots of mold growing on them. Maybe I overwatered them. I don't know. However, the paper roll was always wet and never dried out. Around week 5 or 6, the paper roll pots were overrun with mold, and I had to toss out everything and start over.

I was a complete failure at using the toilet paper roll system. I am open to the suggestion that I could have just done it wrong, but that was my experience.
I had to look for a better seed starting system for me, one that would not grow mold. I ended up finding some YouTube videos on using 3 inch net pots for seed starting. Net pots have slits in them, which allows the excess water to drain out and, in my case, prevented mold from growing. The slits in the net pots also prevent the plants from getting root bound, when the roots circle around the pots until they choke themselves, because the roots will air prune when they reach a slit open to the air.
Most of the plants I start indoors are pepper and tomato plants that are inside for about 8 weeks. The 3-inch net pots are big enough to carry my plants from spouting to transplant in one pot. I have never had mold problems with the net pots with plants even after 8 weeks.
For anyone more interested in this method, here is a good video that I watched on using net pots...
Also going to use egg shells for seed starting.
Since eggshells are so small, you only get days of growth before you need to transplant. I tried it, but it did not work out for me because I grow my plants for about 8 weeks before transplanting. I suppose the eggshell method would be great for plants up to the point of sprouting and maybe a few days longer. In my case, I wanted to find a solution where I did not have to up-pot my plants.
One method I might try this year is the double cup method. I know some people here on the BYC forums really like that method...
No matter what system a person tries, there will be some people that think it's great and others who had problems with it. I prefer the 3-inch net pots, but others here on the BYC forum did not like it and preferred the double cup method.

I guess you just have to try a number of different methods and see what works best for you with the type and length of growing time of your seed starting plants. If you give the toilet paper roll or eggshell methods a try, I would love to hear how it worked out for you.