A fence will not add a tremendous amount of value to your house, so your best solution is your cheapest solution as long you take into account the basics of why people like fences . . . privacy and security. If you have a couple looking at your house and they have a dog or small children, then the condition of your fence is important to them and it should be functional. Those buyers will be drawn to the fence and its condition. Although a white pvc fence is definitely more desirable, if you are selling your home you do not want to incur a $5000 (or more) expense to put one in, in addition to a permit that will be required because it is over 4 feet. Chances are you will not get $5000+ in return for the added fence. If the fence is in good or decent condition but is simply rusty, then you can try buying rustoleum spray paint and paint the fence chrome or silver and it will probably only take about 4-5 cans of spray paint to finish the fence. I dont recommend taking the fence down and NOT putting up a new fence because any buyer with a dog or children will need to put one in and you will suffer in your price. On the flip side, by putting a pvc fence up yourself, you will not get MORE for your house but it will make your house stand out better and it will probably increase the chance of your house selling faster than others. Your most important aspect of selling your home will be the how many bedrooms and baths it has, the overall condition of your house and property. My father has been in the landscaping business for over 40 years and is currently retired (I sold his business last year . . . yey!) Landscaping is SOOOOO important that it IS worth investing in. A well manicured lot with the right shrubs and plantings will attract buyers, especially in Spring. So focus more on that then the fence as it will allow you to reap more rewards. If you want a market analysis of your home or any personal advice, I would welcome the opportunity to come visit you and offer my opinion. My partner and I are Accredited Staging Professionals, and with my landscaping background, as well as legal background, I can properly advise you.
PS One more thing . . . if you decide to put in a new fence, please use a survey. The last thing you need is to go to closing and have to deal with a title issue relating to the fence not being installed on your property lines.