Actually Engineering is the least profitable profession out there, since it is considered to be a "fun" profession
And once people have bought their pets for the achievement, they won't buy them again.
But untill that time, the Pet Bombling and Lil' Smokey will bring in some nice piles of gold
Your just doing it wrong
You know how many people there are on any given server, you know how many alts they have?
Sure, they may only need the pet once for their character, but I get repeat customers all the time buying it for alts to top it off.
By buying out key ingredients to make these pets I have essentially given myself a monopoly on this market and I can set a price that makes a hefty profit for very little work.
Here are some numbers from my server...
Yeti, Cost to craft -~40g - Sells for 200g, 500% profit
Bombling, Cost to craft -~20g - Sells for 200g, 1000% profit
Smoky, Cost to craft - ~20g - Sells for 200g, 1000% profit
Toad, Cost to craft -~15g - Sells for 200g, 1500% profit
I had to purge my database files for Auctioneer because I was getting some extreme lag, so I only have short term results for my sales of these pets,
From 4/25/10 - 4/26/10
Yeti - 6 - 960g profit
Bombling - 6 - 1080g profit
Smoky - 3 - 540g profit
Toad - 5 - 925g profit
That's 3,505g in profit from the last day with only needing less than 30 minutes to craft and post the pets.