Sora 3500 vs Tiagara 4500 brifter
 

The left brifter of my 2012 TCR is broken :( (A plastic part of the holding mechanism broke into two - don't think it can be reliably used even if I glue it back). So I am looking for a new (left) brifter. The Tiagara 4500 9 speed group set is what I am now using. Because I am broke I have no plan to change the derailleur. I think my options are
1) 'Downgrade' to a pair of Sora 3500. I am not sure whether it is really a downgrade.
2) Just replace the left brifter with another Tiagara 4500. This costs about half of option 1 but the problem is I didn't found any 4500 right brifter available for sale and I don't know how long the old one will last.
3) ???
I am not very knowledgeable with bikes so what would be the best option?

I suppose I also need some tutorial on how to replace a brifter.

I will have to look, but I think I have an extra left side 4400, 9 speed brifter. Obviously, not a visual match, but a workable option. Right side is always hard to find. I guess they wear out due to the amount of use compared to the left. Let me know if you have interest and I will look. Cost of shipping only, should be the flat rate package of $8.50/8.95, whatever that rate is.

Thanks a lot. I am in China, so I am not sure about the shipping cost, or how to arrange payment. To compare the 4500 above costs 30 USD, a single Sora left brifter is even slightly cheaper. I guess the main question is, should I replace the right brifter as well?

Shipping it to China definitely cost prohibitive. I would probably replace both of them and have the old one for a spare. I have an Schwinn SS DBX that has mismatched shifters, right 4500 and left 4400. I have replacement for the 4400 If I decide to do that. I am actually leaning towards using the 4500's on an early 90's road bike, it has DT shifters still. I have them in friction mode and am using a 10 speed cassette with them. It shifts great, but I think I would like it more with the STI shifters, That would be a strictly 9 speed set up all the way.