Hi

I have 400D and
lenses are

Canon EF 50mm f/1.8 II
Canon EFS 18-55mm F3.5-5.6 IS Lens
Canon 75-300 f/4-5.6 III USM.

I know these are not great lenses but I bought them as I was starting with photography.
Now I feel that I should upgrade my setup.

At first I thought I should go for good quality lens now and keep 400D for another year or two.Later I saw some low light photos taken with 550D with same lens as mine and I was really impressed.

Now after spending almost 2 years with 400D I wanted to go for new class and started researching for higher class camera. Everybody from whom I asked suggested to go for 7D and buy one all rounder lens like 15-85mm. It would set me back around $2300+.

Another option is go for new/used quality lens for time being and play with it for some time to learn more about quality photography. I do not make any money from photography, it is just hobby so sometime I have to work harder with my other self to justify the cost.

I can stretch my budget to $2500 but will it be really worth spending on 7D+lens?

I am very confused at the moment.

please guide me in right direction.

thanks