Pricing varies a lot from wholesale pricing of around 6-7 cents per message through to full retail pricing of 15-20 cents per message. Like any retail environment, your price is dictated by your value add and by what you think your customer will pay.
Generally clients that are price sensitive will do research online and will find services like Burst SMS. If they are willing to self serve, they may choose to take that route.
Where our resellers come into their own is with value added services. Services like phone support, account management, strategy, creative and training. If you are adding these kind of services, you can resell at a much higher margin than just reselling directly.
As for keywords and numbers you can pretty much charge whatever you want. There is no real standard. We have seen keyword campaigns being charged for $1000's right down to given away as a value add. It really depends on your value add and your relationship with your client.
We have found that reselling SMS is a fairly hands on process when getting a client initially. You will need to speak with them, understand their situation and offer them a solution. Once that is done they will pretty much take care of themselves.
If you are not sure and are not value adding and just want to resell directly just start out adding 100%. This will give you plenty of room for negotiation. Remember once you set your price it is easy to go down but almost impossible to go up.