Actually, that is the "old" system. The one you need to aim for is this one:
Texas Wide Area Radio Network (TxWARN) (P25) Trunking System, Various, Texas - Scanner Frequencies
You will need a P25 Phase II capable scanner. Pearland is on the system I linked, and they are using Phase II talkgroups. You can tell that by looking at the Mode column for the talkgroups. Any TGID with a
T in the mode column is using P25 Phase II. If it is a
D, then the ID is normally used as P25 Phase I. Those labeled with an
E are encrypted, and cannot be monitored with any scanner.
While most of the Brazoria County S.O. talkgroups as labeled as
D, P25 Phase I, there are a coupled labeled as Phase II,
T. Pearland is all Phase II, with a few showing Encrypted. From what I've seen posted, both in the Texas Forum, as well as on the HoustonScan Yahoo group, all users of the
system will be expected tg migrate to Phase II over the next year or two.
Used would be your cheapest option, starting with perhaps the PSR-800 or RadioShack Pro-668. Just bear in mind that the PSR800 was discontinued a number of years ago, when the manufacturer, GRE, went out of business. While the PRO668 is a 'current' model, sold through RadioShack, the Shack has all but abandoned support for scanners. Repair support for either of these could be problematical. If buying used, purchase from a reputable dealer or person, and make sure that the scanner you receive works and has all necessary components.
The Pro668 is manufactured by Whistler, and their equivalent models are the WS1080 and WS1088 (the 1088 has a keypad; the ws1080 does not). For the two Whistler scanners, you can get a no charge upgrade to DMR, which would let you monitor MotoTRBO users, which is used by a lot of business and industrial users, such as the refineries in your area. All of these scanners are handheld (portable) models.
Whistler also has the WS1095, a base/mobile scanner, and the WS1098, which is the same as the 1095, but with a keypad added. They also have the TRX-1 (handheld) and TRX-2 (base/mobile), which are the newest models. All of these current Whistler models a DMR upgrade available, with the TRX-1 & TRX-2 also having a NXDN upgrade available.
In the Uniden product line, the BCD325P2 (handheld) and BCD996P2 (base/mobile) can handle P25 Phase II. The same applies to the Home Patrol-2, as well as the BCD436HP (handheld) and BCD536HP (base/Mobile). All of these, except for the HP-2, have an available DMR upgrade, at a current cost of $60.00