30.4K / 4 persons (since its four of you) = 7.6K for each one of you
7.6k / 4 months (since the job is for 4 months) = 1.9k per month
Those are the hard figures of income. If this is an additional job that is almost an extra 2K from your hobby which should make you happy. If it is with the intention of becoming full time, only you can decide if its worth it or not, as the 2K per month does not include any CPF contributions, so you may be doing it looking at long term relationship with the client etc.
The next way to look at the figures is to look at the profitability of it all. Cost of transport, cost of lights, backgrounds, costs of any models involved etc. Are you expected to do any editing to the shots? costs of retake?
Finally, $30.4K / 4500 = $6.75 / shot (note: I have assumed 4500 products for only 1 shot per product, if all / some products need more than one shot then the results obviously change). Is it worth it? Well, there was a discussion earlier that I think other CS members said they charge from $5-$10 per shot ?? Not sure, look in the rest of the photo biz discussions for that, but whether a shot is worth $5 or $10 it heavily depends on how much work you have to put in, in order to get that shot. If it is just a question of throwing a hammer in a tent and taking a shot, then it might be worth it, but if it is a case of spending lots and lots of time with a shot then it might not be worth it.
On the other hand, if you are between jobs, or want to take sometime off work to to do this, then the above again go out of the window as the motive isn't just about return.
Under the influence of the flu medicine, those are my 2 cents. Hope that it will help you, though I feel I may have asked more than answered.
Me and my friends did the same way to calculate too.. and we realise its cost 6 plus per photo. Editing and design is needed..but at the same time we feared that we are amateur they will not pay us much higher..
Anw what you had said been reali helpful,because i feel that 6+ per product is bit lil ...