Get loads of quotes - the price varies enormously. If your chimney is not pot-lined you will need a flue liner (prices vary by quality, check your quotes). Whilst I understand your need for value, don't get a stove that is either too small or too large for your room (the people who do the quote can do a calculation and work out what KW-output would best suit your needs). Try to spend a bit more and get one that has some degree of heat control, don't want to be sitting with the windows open because you are cooking yourself. The installer doesn't have to be HETAS but you would then need building regs to sign the job off. As its just a bungalow, could you do it yourself (its not rocket science, most people don't think about doing it themselves because they are put off by going up on a high roof) (or do you have any handy friends)?