Renovation for Sale?

I want to sell a house in Cardiff which needs (in some people's eyes) double glazing and a new bathroom and kitchen.
Four Estate Agents have valued it, and said that as it is it might fetch 90k, 100k, 90k and 100k. They all said the cost of renovation wouln't put the price up enough to be worth it, although one did suggest that spending 1k on proffesional decorating might put the value up by more than that.
Do people think they're right?
(It was pointed out in an ourproperty newsletter recently that Estate Agents have an incentive to pursuade vendors to accept low offers because the extra work they have to do if you wait for a good offer isn't worth any extra commission. I don't know if this has a bearing on it.)
Many thanks in advance :-)

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