How about answers from a former tivocommunity moderator and one of the original tivo hackers ?
The short answer is that unless you like hacking around with consumer electronics, dont do this.
1) Watch local over the air digital broadcasts.
You would be able to do this with a 30 minute buffer with dual tuners.
2) Record favorite shows/movies and watch them without commercials (fast forward).
Not likely. While you could get guide data from directv without a sub, recording and playback are disabled for unsubscribed units. There are some hacks you could try where you install an older version of the unit software, do a few other tweaks and install several hacks to simulate a valid directv access card and a regular phone call to directv/tivo, but frankly doing it is relatively illegal and both directv and tivo do "little things" every now and then to hose your unit. In fact, directv changed their guide data format in the last six months and required a software upgrade to all tivo units to have them not periodically and randomly stop recording shows. Not sure if even a well hacked unit will work now with that new data stream.
I have no intention to subscribe to DirecTV.
You should probably look into an HD standalone tivo. Man, thats expensive though. Directv DOES have a really cheap "family package" that has limited channels and IIRC only runs something like $25-30, plus the DVR fee, plus the HD package, which they'll charge you for if you have an HD tivo whether you want it or not. Some folks are getting the HD tivo for free and six months to a year of HD programming for free, plus some free movie channels.
a) Do you like the unit? Is there any reason why it shouldn't be bought?
If you've had experience with a tivo, you'll be right at home. Recording and playback features are far better than the directv DVR, the dish dvr, and anything you can get on a PC. Tivo just owns too many patents on the technology and other companies have to step around those patents so carefully that their products are a bit convoluted.
Only thing that may be a problem is the above mentioned boat-anchoring of the unit by one of the suppliers, either by doing something to your unit or changing the guide data stream. Other item is that many Ebayed units are used and have a balance attributed to them for pay-per-view or unpaid service fees, which could be hundreds of dollars. Yes, directv has these charges follow the unit. If you try to activate a unit with a balance on it, you have to pay the balance before they'll turn it on. Lastly, directv will be changing all of their HD product from MPEG2 encoding to MPEG4 this year, so these older units wont record HD from directv after that and will have to be exchanged for a replacement, with a lengthy service commitment.
b) I can get a used one from EBay for around $170 including shipping. Is $170 a fair price?
Preposterously cheap. These are anywhere from free for long time directv customers to around $250-300 with a 2 year directv service commitment and even at that, its considered a leased unit and you have to send it back if you terminate service. These often run $750-1000 for a new, unsubscribed unit. If you can get one at all, since they've been out of manufacture for a while. A cheap used one is almost certainly either a leased unit that someone is trying to sell or one with a large PPV balance. Which is fine if you're going to hack the heck out of it and you realllly know what you're doing.
c) Is there an easy way to transfer a movie recorded on the unit onto a Laptop DVD?
Not really. A functioning unit (either hacked to heck or subscribed) can be hacked to unlock the encrypting file system and allow for transfers to a PC. But tivotogo isnt currently offered on any of the series 2 based tivo boxes.
