It sounds like you're logging very select areas on your property. Before you go ahead yourself or contract someone else to do the job, sit down and have a think about which areas you don't want damaged. In the longer term, keeping those areas untouched is probably worth more to you than saving a couple thousand dollars. Think 10-20 years from now.
If you do want select areas done, you could well be better off doing it yourself, assuming you have the skills. The gear is only part of the game. You will need to be able to fall(a whole trade by itself), plan out the falling so that you can skid it efficiently, have sufficient labour, know how to limb and buck to sizes that the mill will pay for, stack your logs and be able to load them quickly enough that truck drivers wont charge you waiting time, and get the whole thing done in a manner that is timely. Since you're only doing 5 acre blocks, you maybe be able to just chip away at it when time presents. On the other hand, there's a lot to be said for getting someone in to just git 'er done in short order if they can do the job and not damage your property. Especially if you need to take time off work to do this. Removal of stumps can be a bargaining chip too. If you can have the wood removed, stumps done and the site left exactly as you want it and walk away with nothing spent and nothing earned, that may well be a good outcome for you. To get the same outcome by doing it yourslef you may end up at a big loss.
It seems initially that there's a lot of money to be saved doing it yourself, but labour, fuel, broken things, that extra tool you forgot about, chains, saws, chokers etc etc... all start to add up. Bringing in sub contractors for stumps or other things gets pricey quick. Plus, you may damage a lot of timber trying to get it out. Remember that fallers aren't doing all that well at the moment, but they already have all that gear and do the job every day and have quoted you that price. Shop around a little, but if the prices come back similar then (as unlikely as it sounds) you probably wont do better doing it yourself, even if your time is worth very little.
Long term, the outcome for your property is going to be the big thing. In 10 or 20 years time, if it wasnt handled well, the cost of correcting it will be enormous. It may seem like a good bit of quick money, but that same money could easily be earned working 6 months for someone else. I'd be thinking about how you want the property to be, and working from there.
Shaun