Informix 7.3 backup utility for SCO

I'm a new user to Informix, and I need a backup solution for SCO 5.0.5 running 7.3 Online-Workgroup. We have about 50 gig of Informix tables to backup. I'm told the ontape command would be too slow. I'm told 7.3 has the onbar utility and that would be the best solution. I looked at Lagato's page, but they only support AIX, HP and Solaris. I got a price quote from ArcServe and they want $5700 per server. We have two servers and $11,400 dollars for backup software is just too much. ArcServe prices their software based on the server size, which in our case is a 4 processor Xeon server. Gary Quiring