The neti pot is going to be very tough on a 2 year old. He probably can't blow his nose very well and I think it will just frustrate him and/or freak him out. It's great for older kids and adults who can handle the "stuffed" feeling, hold still while it drips out, and then blow out.
Honestly, I'd put him on a comprehensive nutritional product like Reliv NOW for Kids - it's used world-wide to give kids the missing ingredients in their diet. The AMA says everyone needs to supplement because even "good eaters" don't get what they need due to pollution, depleted soils, farming techniques, and so on. Reliv has all the nutrients he needs and all together - that's key. It's made here in the US, the surprise FDA inspections are stellar, and there are no drugs or chemicals - just food. The kids' product is delicious - vanilla or chocolate, and you mix it in water, milk, whatever you want. All my friends with kids on it say their kids are done with colds, sore throats, tonsil problems, and so on. One friend's son was on a nebulizer a lot and had pneumonia-like symptoms 3 weeks out of 4 when he was 1 year old. He has been virtually illness-free for 6 years. I've met many others in the same situation.
The product is researched, based on clinical trials, has the strongest purity of anything else made, and is under the supervision of a world renowned food scientist who was on the team that developed Enfamil and ProSoBee formulas - so he knows infant nutrition. The company has received many awards for its business ethics and humanitarian efforts, and is on the board of the Council for Responsible Nutrition.
The best thing is, you buy the product from a nutritional consultant who is trained and who will help you with quantities, tips, even recipes for picky eaters. There is a 30-day guarantee and the follow-up is fantastic. There's nothing you can buy on a store shelf that has that kind of support. Any company can have a great website but it doesn't mean they are a good company. Reliv is top notch and the help you get is unmatched.
I swear by it - my family hasn't been sick in the 3 years we've been on the products. I'd be happy to help you.